Mask vent

ABSTRACT

A vent arrangement is provided to a mask or associated conduit to discharge exhaled gas from the mask to atmosphere. The vent arrangement is structured to diffuse the exhaust vent flow to produce less air jetting, thereby increasing the comfort of the patient and their bed partner. For example, the vent arrangement may include one or more grill components and/or media constructed and arranged to diffuse vent flow.

CROSS-REFERENCE TO APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/475,941, filed Sep. 3, 2014, currently pending, which is acontinuation of U.S. patent application Ser. No. 13/773,846, filed Feb.22, 2013, now U.S. Pat. No. 8,851,075, which is a continuation of U.S.patent application Ser. No. 12/230,120, filed Aug. 22, 2008, now U.S.Pat. No. 8,397,727, which claims the benefit of U.S. ProvisionalApplication Nos. 61/129,253, filed Jun. 13, 2008, 61/064,405, filed Mar.4, 2008, and 60/957,766, filed Aug. 24, 2007, each of which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The field of the invention relates to mask vents used for Non-invasivePositive Pressure Ventilation (NPPV) and for continuous positive airwaypressure (CPAP) therapy of sleep disordered breathing (SDB) conditionssuch as obstructive sleep apnea (OSA).

BACKGROUND OF THE INVENTION

Treatment of sleep disordered breathing (SDB), such as obstructive sleepapnea (OSA), by continuous positive airway pressure (CPAP) flowgenerator systems involves the continuous delivery of air (or otherbreathable gas) pressurized above atmospheric pressure to the airways ofa human or other mammalian patient via a conduit and a mask. Typically,the mask fits over the mouth and/or nose of the patient. Pressurized airflows to the mask and to the airways of the patient via the nose and/ormouth. As the patient exhales, carbon dioxide gas may collect in themask. A washout vent in the mask or conduit discharges the exhaled gasfrom the mask to atmosphere.

The washout vent is normally located in the mask or near the mask in thegas delivery conduit coupled to the mask. The washout of gas through thevent to the atmosphere removes exhaled gases to prevent carbon dioxidebuild-up, and hence “rebreathing”, which represent a health risk to themask wearer. Adequate gas washout is achieved by selecting a vent sizeand configuration that allows a minimum safe washout flow at a lowoperating CPAP pressure, which typically can be as low as 4 cm H₂O foradults and 2 cm H₂O for children.

Noise is a significant issue in CPAP treatment for the patient and/orthe patient's bed partner. Excessive noise can lead to patients beingnon-compliant with the CPAP therapy. One source of noise is the exhaustthrough the vent in the mask or conduit. The flow of gas through thevent creates noise as it exits to and interacts with the atmosphere.Noise can adversely affect patient and bed-partner comfort, depending onboth the magnitude and character of the noise. Further, bi-level gasdelivery regimes tend to generate more noise than do constant level gasdelivery regimes. This is thought to be due to the extra turbulencecreated by the gas accelerating and decelerating as it cycles betweenrelatively low and relatively high pressures in the bi-level gasdelivery systems.

“Air Jetting” out of the vents is also a significant issue. Air jetting,or lack of diffusion in the vent, involves a high-velocity jet stream ofexhaust gases blowing onto obstacles (such as bedding, bed partner, oreven onto the mask wearer themselves). This not only causes asignificant increase in noise due to a sudden change in velocity of theexhausted air, but the high-velocity jet stream also creates greatdiscomfort for the bed partner or mask wearer as a result of “windchill”.

Exemplary devices to reduce noise associated with gas washout areRespironics' Whisper Swivel II, Weinmann's SilentFlow 2, Weinmann'sNoise Suppressor, ResMed MAP's Aero-Click, Fisher & Paykel's Aclaim 2,and Drager's E-Vent.

Other exemplary devices to reduce noise associated with gas washout areResMed's Gore-Tex membrane vent, ResMed's stainless steel laser-cutorifices, and ResMed's Porex or sintered plastic vent. For example, seePCT Publication No. WO 2006/069415, published Jul. 6, 2006, which isincorporated herein by reference in its entirety.

There is a long felt and continuing need to reduce the noise associatedwith the washout or venting of exhaled gases. Reducing the noise of gasbeing exhausted from a mask or conduit can significantly improve theuser friendliness of the CPAP treatment.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a vent insert for a mask. Thevent insert includes a base including one or more cross-bars and one ormore grill components provided to the base. Each grill componentincludes a grill. The one or more grill components are stackable on topof the base and selectively rotatable with respect to the base to adjustthe angle of the one or more grills of the one or more grill componentswith respect to the one or more cross-bars of the base so as toselectively define fine, porous vent orifices through the insert.

Another aspect of the invention relates a vent insert for a mask. Thevent insert includes a base adapted to be supported within an outletopening in the mask, one or more media provided to the base, and a coverincluding a cross-bar provided to the base to retain the at least onemedia within the base. The base includes one or more base cross-bars.

Another aspect of the invention relates to a mask including a maskcomponent including a venting area having a plurality of vent orificesand a cover provided to the mask component. The cover includes a ventingarea having a plurality of vent clusters. Each vent cluster includes atubular spigot that defines an orifice and a plurality of arcuate shapedorifices regularly spaced and separated from one another along a circleabout the spigot. The cover is attachable to the mask component suchthat each vent cluster of the cover is aligned with a respective ventorifice of the mask component.

Another aspect of the invention relates to a mask including a maskcomponent including a plurality of vent orifices and a cover provided tothe mask component. The cover includes a plurality of vent clusters.Each vent cluster of the cover is aligned with a respective vent orificeof the mask component.

Another aspect of the invention relates to a mask including a maskcomponent including a plurality of vent orifices and a cover provided tothe mask component. The cover includes a plurality of vent orifices.Each orifice of the mask component corresponds to a plurality oforifices of the cover.

Another aspect of the invention relates to a mask assembly including amask having a mask interior, an air delivery tube provided to the mask,and a shroud covering a portion of a length of the air delivery tube.The shroud and air delivery tube define a vent passage there between.The vent passage has an annular cross-section and including an inlet incommunication with the mask interior and an outlet opening toatmosphere.

Another aspect of the invention relates to a mask assembly including aninterfacing structure, a manifold positioned on a top of the patient'shead and adapted to connect with a supply of breathable gas, and twoinlet conduits extending along respective sides of the patient's face.The two inlet conduits are connected to the manifold and adapted todeliver the supply of breathable gas to the interfacing structure. Eachinlet conduit and/or the manifold includes one or more vent orifices forgas washout.

Another aspect of the invention relates to a mask frame including a mainbody and a plurality of vent orifices distributed over a majority of themain body.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component, at least one vent orifice provided to themask component, each vent orifice including a vent exit, and aprotrusion provided to the mask component adjacent each vent exit. Theprotrusion may be pyramidal, conical, or dome shaped. Such arrangementprovides adjacent vent orifices adapted to deliver streams of exhaustgas that are substantially directionally perpendicular to each other.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component and at least one vent orifice provided to themask component. Each vent orifice has an hourglass shape including aninlet portion with a convergent configuration in which the orificetapers from larger to smaller cross-section along its entire length andan outlet portion with a divergent configuration in which the orificetapers from smaller to larger cross-section along its entire length. Theinlet portion is continuous with the outlet portion, and the inletportion and outlet portion include substantially similar lengths.

Another aspect of the invention relates to a mask including a mask frameincluding a mask interior, at least one vent orifice provided to theframe, and an obstruction provided within the mask interior andpositioned in front of the at least one vent orifice.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component and a mesh structure provided to the maskcomponent. The mesh structure is woven to create a plurality of ventorifices. In an embodiment, the mesh structure includes stainless steelmesh or stainless steel wires. In an alternative embodiment, the meshstructure includes woven fabrics constructed of polypropylene,polycarbonate, polyamide, polyesters, polytetrafluoroethylene, or3-dimensional spacer fabrics.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component including a dome-shaped portion and aplurality of vent orifices provided to the dome-shaped portion. In anembodiment, the orifices include a central orifice and a plurality oforifices arranged in a circle about the central orifice.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component and a plurality of vent orifices provided tothe mask component. Adjacent vent orifices have a different diameter.

Another aspect of the invention relates to a vent insert for a maskincluding a sheet having a plurality of perforated sections. Theperforated sections are adapted to be folded against each other toproduce vent orifices through the perforated sections.

Another aspect of the invention relates to a vent arrangement for amask. The vent arrangement includes a mask component and a plurality ofadjacent protrusions provided to the mask component. Each of theprotrusions includes one or more vent openings. The vent openings of theprotrusions are arranged so that vent flow is directed in differentdirections, into one another, and/or slightly offset from one another tocreate diffuse air flow.

Another aspect of the invention relates to a vent arrangement for amask. The vent arrangement includes a mask component and one or moreprotrusions provided to the mask component. Each of the protrusionsincludes a plurality of vent openings. The vent openings of eachprotrusion are arranged so that vent flow is directed in differentdirections, into one another, and/or slightly offset from one another tocreate diffuse air flow.

Another aspect of the invention relates to a vent arrangement for amask. The vent arrangement includes a mask component and one or morerecesses provided to the mask component. Each of the recesses includes aplurality of vent openings. The vent openings of the recesses arearranged so that vent flow is directed in different directions, into oneanother, and/or slightly offset from one another to create diffuse airflow.

Another aspect of the invention relates to a vent arrangement for a maskincluding a mask component and a vent cap provided to the maskcomponent. The vent cap includes a base wall and a dome or raisedportion that extends upwardly from the base wall. The dome or raisedportion includes a side wall with multiple vent holes arranged along theside wall. The vent holes are open in use at least during the inhalationand exhalation phases of the user's breathing cycle.

Another aspect of the invention relates to a mask system including amask, an elbow provided to the mask, and a baffle provided between themask and the elbow. The elbow includes an annular side wall and aplurality of vent holes for gas washout arranged on the annular sidewall. The baffle includes an annular configuration with one or moreundulations and/or guides structured to guide washout gas along a flowpath to the vent holes.

Another aspect of the invention relates to a mask system including amask component including one or more openings for gas washout and a ventcomponent provided to the mask component. The vent component includesone or more tracks or grooves along its outer surface adapted to guidegas washout. The vent component is adapted to cover the one or moreopenings in the mask component so that gas washout escapes along the oneor more tracks or grooves between an outer surface of the mask componentand the vent component.

Another aspect of the invention relates to a vent arrangement for a maskincluding a vent component adapted to be provided to the mask and atleast partially define one or more openings for gas washout, and atleast one port cap integrated with the vent component. Each port cap isadapted to engage a respective port provided to the mask.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1-1 is a schematic view illustrating vent flow for a single largeoutlet as known in the art;

FIG. 1-2 is a schematic view illustrating vent flow for a diffused venthaving a branched outlet according to an embodiment of the presentinvention;

FIG. 2-1 is a schematic view of a mask including semi-remote ventingaccording to an embodiment of the present invention;

FIGS. 2-2-1 and 2-2-2 are perspective views of a mask including ventingalong inlet conduits according to embodiments of the present invention;

FIGS. 2-3-1 and 2-3-2 are perspective views of a mask including ventingat the top of the patient's head according to embodiments of the presentinvention;

FIG. 2-4 is a perspective view of a completely vented frame according toan embodiment of the present invention;

FIG. 2-5 is a schematic view of a mask including protrusions adjacentvent exits according to an embodiment of the present invention;

FIG. 2-6 is a schematic view of an hourglass-shaped vent orificeaccording to an embodiment of the present invention;

FIG. 2-7-1 is a perspective view illustrating flow through the ventinlet of ResMed's Mirage mask;

FIG. 2-7-2 is a perspective view illustrating an obstruction in front ofa vent inlet according to an embodiment of the present invention;

FIG. 2-8 is a top view of a stainless steel mesh including vent orificesaccording to an embodiment of the present invention;

FIGS. 2-9-1 and 2-9-2 are schematic views of orifices distributed over adome according to an embodiment of the present invention;

FIGS. 2-10-1 and 2-10-2 are schematic views of orifices definingdifferent levels of velocity shrouds according to an embodiment of thepresent invention;

FIG. 2-11 is a schematic view of a slot-orifice vent according to anembodiment of the present invention;

FIG. 2-12 is a schematic graph illustrating a diameter range for anorifice to balance cleanability and quietness;

FIGS. 2-13-1 to 2-13-3 are schematic views of a foldable vent insertaccording to an embodiment of the present invention;

FIGS. 2-14-1 to 2-14-3 are various views of a stackable vent insertaccording to an embodiment of the present invention;

FIGS. 2-15-1 to 2-15-3 are various views of a vent insert including asingle layer of media according to an embodiment of the presentinvention;

FIGS. 2-16-1 to 2-16-3 are various views of a vent insert includingdouble layer media according to an embodiment of the present invention;

FIGS. 2-17-1 to 2-17-3 are various views of a vent insert includingpleated media according to an embodiment of the present invention;

FIGS. 2-18-1 to 2-18-3 are various views of a vent insert as a commoncomponent according to an embodiment of the present invention;

FIG. 2-19 is a schematic view of a vent including a centralhigher-velocity stream and outer lower-velocity streams;

FIG. 2-20 is a schematic view of a dual flow mouthpiece for an aircompressor demonstrating an application of the theory in FIG. 2-19;

FIGS. 2-21-1 to 2-21-4 are various views of an elbow assembly accordingto an embodiment of the present invention;

FIG. 2-22-1 illustrates a vent arrangement including a plurality ofprotrusions with vents according to another embodiment of the presentinvention;

FIG. 2-22-2 is a cross-sectional view of the vent arrangement shown inFIG. 2-22-1;

FIGS. 2-22-3 illustrates a vent arrangement including a plurality ofprotrusions with vents according to another embodiment of the presentinvention;

FIG. 2-22-4 is a cross-sectional view of the vent arrangement shown inFIG. 2-22-3;

FIG. 2-22-5 is a schematic view of a mold for molding the protrusions ofFIGS. 2-22-3 and 2-22-4;

FIG. 2-23 is a cross-sectional view of a vent arrangement including arecess with vents according to another embodiment of the presentinvention;

FIG. 2-24 illustrates a vent arrangement including a plurality ofdome-shaped protrusions with vents according to another embodiment ofthe present invention;

FIG. 2-25 illustrates a vent arrangement including a plurality ofelongated three-dimensional trapezoidal-shaped protrusions with ventsaccording to another embodiment of the present invention;

FIG. 2-26 illustrates a disk-like vent arrangement according to anotherembodiment of the present invention;

FIG. 3 is a chart illustrating sound power for vent media according toembodiments of the invention;

FIG. 4-1A is a top view of a vent cap according to an embodiment of thepresent invention;

FIG. 4-1B is a top view of a vent cap according to another embodiment ofthe present invention;

FIG. 4-1C is a top view of a vent cap according to another embodiment ofthe present invention;

FIGS. 4-2A to 4-2C are top, bottom, and side schematic views of the ventcap shown in FIG. 4-1B;

FIGS. 4-3A to 4-3C are top, side, and perspective views of the vent capshown in FIG. 4-1B;

FIGS. 4-4A to 4-4B are perspective views of a vent cap according toanother embodiment of the present invention;

FIGS. 4-5A to 4-5B are top and side views of an elbow according to anembodiment of the present invention;

FIGS. 4-6A to 4-6B are top and side schematic views illustrating anunlocked position of a vent cap with respect to an elbow according to anembodiment of the present invention;

FIGS. 4-7A to 4-7B are top and side schematic views illustrating alocked position of a vent cap with respect to an elbow according to anembodiment of the present invention;

FIG. 4-7C is a perspective view showing a vent cap on an elbow accordingto an embodiment of the present invention;

FIG. 4-7D is a perspective view showing a vent cap and elbow accordingto an embodiment of the present invention;

FIG. 5-1 is a schematic side view of a baffle provided between a maskand elbow according to an embodiment of the present invention;

FIG. 5-2 is a schematic plan view of a baffle according to an embodimentof the present invention;

FIG. 5-3-1 is an exploded view showing a baffle and elbow according toan embodiment of the present invention;

FIG. 5-3-2 is a cross-sectional view of the baffle and elbow shown inFIG. 5-3-1 in an assembled configuration;

FIG. 5-4 is a schematic view of a bayonet connection according to anembodiment of the present invention;

FIG. 5-5 is a schematic view of a bayonet connection according toanother embodiment of the present invention;

FIG. 5-6-1 is a schematic side view of a coil-type baffle according toan embodiment of the present invention, the coil-type baffle in anuncoiled position;

FIG. 5-6-2 is a schematic side view of the coil-type baffle shown inFIG. 5-6-1 with the coil-type baffle in a coiled position;

FIGS. 5-7-1 and 5-7-2 are top and bottom perspective views of an elbowaccording to an embodiment of the present invention;

FIG. 5-8-1 is a perspective view of a baffle according to an embodimentof the present invention;

FIG. 5-8-2 is an exploded view showing a baffle and elbow according toan embodiment of the present invention;

FIG. 5-8-3 is a cross-sectional view of a baffle and elbow according toan embodiment of the present invention;

FIG. 5-9-1 is a perspective view of a vent ring and elbow according toanother embodiment of the present invention;

FIG. 5-9-2 is a top view of the vent ring of FIG. 5-9-1;

FIG. 5-9-3 is a top view of the vent ring of FIG. 5-9-1 in a deformedposition;

FIG. 5-9-4 is a perspective view showing assembly of the vent ring andelbow of FIG. 5-9-1;

FIG. 5-9-5 is a cross-sectional view of the assembled vent ring andelbow of FIG. 5-9-1;

FIG. 5-9-6 is a side view of the vent ring and elbow of FIG. 5-9-1;

FIG. 5-10-1 is a perspective view of a vent ring according to anotherembodiment of the present invention;

FIG. 5-10-2 is a perspective view showing assembly of the vent ring ofFIG. 5-10-1 to an elbow;

FIG. 5-10-3 is an enlarged top view of the vent ring of FIG. 5-10-1;

FIG. 5-11-1 is a perspective view of a vent ring and elbow according toanother embodiment of the present invention;

FIG. 5-11-2 is a perspective view showing the assembly of the vent ringand elbow of FIG. 5-11-1;

FIG. 5-12-1 is a perspective view of a vent ring and elbow according toanother embodiment of the present invention;

FIG. 5-12-2 is a perspective view showing the assembly of the vent ringand elbow of FIG. 5-12-1;

FIGS. 6-1 to 6-7 are various views of an elbow including a ventarrangement according to another embodiment of the present invention;

FIG. 7-1 is a rear perspective view of a plug-type vent and frameaccording to another embodiment of the present invention;

FIG. 7-2 is a top perspective view of the plug-type vent and frame ofFIG. 7-1;

FIG. 7-3 is a perspective view of the plug-type vent of FIG. 7-1;

FIG. 8-1 is a rear perspective view of a plug-type vent and frameaccording to another embodiment of the present invention;

FIG. 8-2 is a top perspective view of the plug-type vent and frame ofFIG. 8-1;

FIG. 8-3 is a perspective view of the plug-type vent of FIG. 8-1;

FIG. 9-1 is a perspective view of a plug-type vent and frame accordingto another embodiment of the present invention;

FIG. 9-2 is an exploded view of the plug-type vent and frame of FIG.9-1;

FIG. 9-3 is a perspective view of the plug-type vent of FIG. 9-1; and

FIG. 9-4 is a side view of the frame of FIG. 9-1.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodimentswhich may share common characteristics and features. It is to beunderstood that one or more features of any one embodiment may becombinable with one or more features of the other embodiments. Inaddition, any single feature or combination of features in any of theembodiments may constitute additional embodiments.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise”, “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that the PAPdevices or blowers described herein may be designed to pump fluids otherthan air.

1. Mask Embodiments

A range of masks (also referred to as patient interfaces or masksystems) are known including nasal masks, nose & mouth masks, full-facemasks and nasal prongs, pillows, nozzles & cannulae.

Masks typically include a rigid or semi-rigid portion (often referred toas a shell or frame) and a soft, patient contacting portion adapted toform a seal with the patient's nose and/or mouth (often referred to as acushion or nasal prong arrangement). An elbow may be provided to theframe and adapted to be connected to an air delivery tube (not shown)that delivers breathable gas to the patient. However, it should beappreciated that other mask arrangements are possible, e.g., not rigid(e.g., constructed of cloth).

One or more washout vents are provided to the mask or associated conduitto discharge exhaled gas from the mask to atmosphere. In embodiments,the one or more vents may be provided to the frame and/or the elbow ofthe mask. One or more vents in the associated conduit is also possible.

2. Vent Embodiments

The following describes alternative embodiments of vent arrangements forgas washout from a mask.

It should be appreciated that each vent arrangement may be adapted foruse with any suitable interface type, e.g., nasal masks, nose & mouthmasks, full-face masks, nasal prongs, etc. In addition, each ventarrangement may be adapted for use in any suitable portion of the mask,e.g., frame, elbow, conduit, etc.

In an embodiment, the vent arrangement may be a common componentstructured for use in multiple interface types. For example, the ventarrangement may be adapted for use in a mask elbow, a mask frame for afull-face mask, and a frame for a nasal prong arrangement. Such anarrangement is described in greater detail below.

2.0 Diffused Vents

The vent arrangements described below may be structured to diffuse theexhaust vent flow. Increased diffusion of the exhaust vent flow maycause less air jetting onto bed clothes and bed partners, and may alsoproduce less noise.

For example, relatively large aperture vent orifices with relativelyshort flow path lengths produce high velocity, undeveloped flow whichcan generate excessive noise. FIG. 1-1 illustrates vent flow for asingle large outlet 2. As illustrated, the exhaust vent flow produces alarge core stream 4 with a large mixing area 6. High frequency noise isindicated at 7 and low frequency noise is indicated at 8.

In contrast, FIG. 1-2 illustrates vent flow for a diffused vent having abranched outlet 10 according to an embodiment of the present invention.As illustrated, the core stream 14 and mixing area 16 is significantlysmaller than that of the large outlet 2 of FIG. 1-1. In addition, thenoise (e.g., high frequency noise from air streams contacting very lowvelocity ambient air streams) travels significantly less from thebranched outlet 10 than that of the large outlet 2 of FIG. 1-1. At adistance x from the outlet, the vent flow of outlet 2 has a highervelocity that produces more noise if the air flow is interrupted (e.g.,by the patient's bed clothes) while the vent flow of branched outlet 10has a lower velocity that produces less noise if the air flow isinterrupted. Noise is caused by the sudden change in high velocity ofthe exiting air contacting the very low velocity ambient air, so theslower velocity created by diffusion reduces the velocity change andhence the noise. Thus, the branched outlet 10 diffuses the vent flow toproduce lower velocity flow than that of the large outlet 2 of FIG. 1-1which may produce less noise. Also, the diffused vent flow produces lessnoise with an obstruction, e.g., vent flow against bed sheet, pillow,etc.

Each of the vent arrangements described below may include one or more ofthe following properties: high level of diffusion to prevent ventjetting and to reduce the sensitivity of vent noise to obstructions,quietness, maintain vent flow under humidified conditions, maintain ventflow under saturated conditions, avoid vent blockage from grease anddebris, minimize CO₂ rebreathing, physical size to fit the smallestmasks, low cost, manufacturability, no particulates, robustness,cleanable and disposable, usability, durability and lifespan, compliancewith existing flow generators, maintainability, biocompatibility, resistbacterial growth, quality of noise, and/or perception of reliability.

2.1 Semi-Remote Venting

FIG. 2-1 illustrates a mask including a vent arrangement according to anexample of the present invention. In the illustrated example, the mask20 includes an air delivery tube 22 having a mask end provided to themask and a supply end provided to a flow generator adapted to deliverbreathable gas to the mask. A short outer tube or shroud 25 covers aportion of the air delivery tube 22, e.g., from the mask end.

An interior surface of the outer tube 25 and an exterior surface of theair delivery tube 22 form a gap there between that defines a ventpassage 26. The vent passage 26 includes an inlet 26(1) in fluidcommunication with the mask interior and an outlet 26(2) opening toatmosphere.

The vent passage 26 includes an annular cross-section, and the outlet26(2) of the vent passage 26 is remote from the mask 20 and faces awayfrom the mask and the patient. In an embodiment, the vent passage 26 maytaper from the inlet to the outlet, e.g., to reduce noise.

Also, in an embodiment, the outer tube 25 may be perforated to includeone or more small, diffused vent orifices 28 for gas washout.

2.2 Venting Along Inlet Conduits

FIGS. 2-2-1 and 2-2-2 illustrate a mask 220 including an interfacingstructure 230 and two tubes or inlet conduits 232 extending alongrespective sides of the patient's face and adapted to deliver breathablegas to the interfacing structure 230. Exemplary embodiments of such amask are disclosed in U.S. patent application Ser. No. 11/878,933, filedJul. 27, 2007, and Ser. No. 11/878,932, filed Jul. 27, 2007, each ofwhich is incorporated herein by reference in its entirety.

According to an embodiment of the present invention, each of the inletconduits 232 may include one or more vent orifices 228 for gas washout.For example, the orifices 228 may be provided in a region adjacent theinterfacing structure 230 (see FIG. 2-2-1) and/or the orifices 228 maybe provided along the length of each conduit 232 (see FIG. 2-2-2). Theorifices 228 may be arranged in any suitable pattern on the conduit(e.g., random, aligned in columns, etc.) and may be arranged to directwashout gas in any suitable direction. In addition, each conduit mayhave any suitable number of orifices, and each orifice may have anysuitable cross-sectional configuration along its length (e.g., tapered).

2.3 Venting at the Top of the Head

In another example, a vent arrangement for a mask may be provided at thetop of the patient's head in order to redirect vent exhaust away fromthe patient and bed partner. For example, in the mask described above inFIGS. 2-2-1 and 2-2-2, the inlet conduits extend to the top of thepatient's head and are coupled to one another via a manifold. Accordingto an embodiment of the present invention, each of the inlet conduits232 may include one or more vent orifices 228 for gas washout in aregion adjacent the manifold 235 (see FIG. 2-3-1) and/or one or morevent orifices 228 may be provided in the manifold 235 itself (see FIG.2-3-2).

The orifices 228 may be arranged in any suitable pattern on the conduit(e.g., random, aligned in columns, etc.) and may be arranged to directwashout gas in any suitable direction. In addition, each conduit mayhave any suitable number of orifices, and each orifice may have anysuitable cross-sectional configuration along its length (e.g., tapered).

2.4 Completely Vented Frame

In another embodiment, a shown in FIG. 2-4, the mask frame 324 for amask may include multiple vent orifices or clusters of vent orifices 328spread out all over the frame 324 to diffuse gas washout. The ventorifices may be clustered in selected regions of the frame and/or thevent orifices may be distributed over the frame. In addition, the framemay have any suitable number of orifices, and each orifice may have anysuitable cross-sectional configuration along its length (e.g., tapered).

2.5 Protrusions Adjacent Vent Exits

In another embodiment as shown in FIG. 2-5, the mask may includemultiple, adjacent vent orifices 428, and pyramidal or conical shapedprotrusions 440 may be provided adjacent the vent exits to fill inviscous shearing regions and therefore reduce noise.

It is the viscous shearing region just outside the vent exits ofmultiple clusters of orifices that generates vent noise, i.e., thepyramidal/conical region in between adjacent vent orifices. According toan embodiment of the present invention, protrusions 440 are provided tofill in these voids to reduce this shearing region and therefore reducenoise generated.

2.6 Hourglass-Shaped Orifice

In another embodiment, as shown in FIG. 2-6, the mask may includemultiple, closely spaced vent orifices 528 with each vent orifice 528having an hourglass shape, i.e., vent orifice 528 including thecombination of a convergent orifice and a divergent orifice.Specifically, each vent orifice 528 includes an inlet portion 528(1)with a convergent configuration (i.e., orifice tapers from larger tosmaller cross-section) and an outlet portion 528(2) with a divergentconfiguration (i.e., orifice tapers from smaller to largercross-section). The inlet portion 528(1) to the orifice may be roundedoff or include a radius to minimize entrance effects. Hourglass-shapedorifices enable longer holes to be molded as the convergent inlets anddivergent outlets are formed from tooling (pins) on opposite sides thatmeet at the “neck”. Longer holes provide a longer flow path which helpsto fully develop the flow.

2.7 Reduce High Velocities Entering the Vent Inlet

In another embodiment, an obstruction may be provided in front of theinlet to the vent orifice to significantly reduce the vent inletvelocity and therefore reduce vent noise.

For example, FIG. 2-7-1 illustrates ResMed's Mirage mask 620 including amask frame 624, an insert 627 including a plurality of vent orifices 628provided to the frame, and an inlet tube 622 provided to frame andadapted to deliver pressurized gas. In such embodiment, the direct flowof air into the vent inlets of the orifices 628 produces high velocity,laminar flow which can generate relatively high vent noise.

According to an embodiment of the present invention, as shown in FIG.2-7-2, an obstruction 638 (e.g., side wall extending from frame) may beplaced in front of the vent inlets of the orifices 628 to createresistance and reduce flow velocity and generated vent noise. That is,the obstruction 638 reduces high velocity gas from directly entering theorifices 628, which reduces noise.

This arrangement is counter-intuitive as it challenges the notion thateverything within the mask chamber should remain as undisturbed andlaminar as possible, which results in high velocity flow into the vents.Any obstructions should still be “smoothly contoured” to avoid excessivenoise from turbulence. Obstructions create a more tortuous,labyrinth-like path for the exhaust gases to flow through. The increasedresistance of these paths reduce the kinetic energy, and thereforevelocity of the flow. The reduced velocity results in reduced noise andless air jetting. Reduced velocity, fully developed laminar flow is mostdesirable.

2.8 Reduce Exit Vent Flow Velocity

The sound power of the vents is very sensitive to exit vent flowvelocity. For example,

$W \propto {\frac{S\;\rho\; V^{4}}{c}\mspace{14mu}{or}\mspace{14mu} W} \propto \frac{S\;\rho\; V^{8}}{c^{5}}$(depending on monopole or quadrupole source, respectively) where:W=radiated sound power; S=cross-sectional area of the vent; ρ=density ofair; V=vent exit flow velocity; and c=speed of sound.

According to embodiments of the invention, the exit vent flow velocitymay be reduced in order to reduce noise.

2.9 Stainless Steel Mesh

In another embodiment, as shown in FIG. 2-8, a portion of the mask maybe provided with a stainless steel mesh 742 that includes plurality ofvent orifices 728 for gas washout. In an embodiment, the stainless steelmesh 742 includes wires 743 that are woven with one another to createthe mesh structure with the plurality of vent orifices 728. The ventingor permeability provided by the mesh 742 may depend on the wire size andthe tightness of the weave, e.g., orifice area may be around 25% of thetotal area of the mesh and the minimum orifice size may be dictated bythe minimum stainless steel wire diameter as the wires weave in and outof one another. In alternative embodiments, the mesh may be constructedfrom other woven fabrics or meshed media, e.g., polypropylene,polycarbonate, polyamide (e.g., nylon), polyesters,polytetrafluoroethylene (e.g., Teflon), 3-dimensional spacer fabrics.

2.10 Alarm to Signal Vent Replacement/Washing

Vent arrangements including fine meshing, textiles, fragile constructionof materials, and/or very small orifices are potentially prone toblockage from dirt and bio-build-up or damage. Therefore, the usereither needs to regularly wash the vents or replace them to ensure thatadequate vent flow is maintained for good CO₂ washout.

According to an embodiment of the present invention, the positive airwaypressure device (PAP) device or flow generator may include an alarm tosignal the user in the event of reduced vent flow so that the user knowswhen to replace/wash the vent arrangement. Fail-safe modes are also waysto ensure that the user is cautioned to replace/wash their vents. Forinstance, if the vent media were assembled to the mask with an adhesive,the adhesive could be CO₂-sensitive/H₂O-sensitive which would graduallydissolve with a pre-determined exposure to exhaled CO₂/humidity.Eventually, the vent media may become loose and may expose a gap(between the vent media and mask) which would still allow for theexhaustion of exhaled gases, however, it may be quite noisy. Anotherfail-safe mode that is somewhat similar is to ensure that the ventcomponent has a preloaded assembly feature that gradually relaxes (i.e.,creeps) with time resulting in a loosely fitting vent that would exposea gap between the vent component and the mask interface to which it isassembled.

2.11 Hydrophobic Coating

In another embodiment, a hydrophobic coating may be provided on theinside of the vent material, i.e., hydrophobic coating along the ventinlets. The hydrophobicity of the vent inlets will help to prevent thevent orifices from being blocked by humidity.

2.12 Cluster of Fine Vent Orifices Distributed Over a Dome

As shown in FIGS. 2-9-1 and 2-9-2, the mask may include a dome-shapedportion 845 and a cluster of fine vent orifices 828 distributed over thedome-shaped portion 845 for gas washout. In the illustrated embodiment,the orifice arrangement includes a central orifice and a plurality oforifices arranged in a circle about the central orifice. As illustrated,the orifices 828 are separated from one another by a distance x and eachorifice 828 has a diameter size d. However, other suitable orificearrangements are possible. For example, the orifices may be distributedover the dome in other manners, e.g., random, linearly, other patterns,etc.

In an embodiment, Computational Fluid Dynamics (CFD) may be used tomodel variation in orifice size and orifice separation to achieve anoptimum balance of these two parameters in an attempt to mimic thediffusive properties of membranes such as Gore-Tex™.

In terms of manufacturability, the orifices may be molded out of a sheetof silicone rubber or elastomer and the sheet may be subsequentlystretched over a support structure or railing (provided to the mask)structured to curve the sheet into a dome shape. However, the ventarrangement may be constructed in other suitable manners.

2.13 Adjacent Vent Orifices of Different Size and Length

In another embodiment, the mask may include multiple vent orifices withadjacent vent orifices having a different size, e.g., alternatingsmaller and larger vent orifices. Such arrangement may reduce noise inuse.

The amount of generated vent noise is very sensitive to the differencein velocity between the exit vent flow and the velocity of the airsurrounding the exit vent stream (i.e., typically the ambient air, whichis relatively still).

By having variation in the size and length of adjacent vent orifices,differences in adjacent exit vent velocities are created since jetstream velocity is dependent on orifice size and flow path length. Thiscan effectively reduce the velocity gradient between the exhaust streamsand the still ambient air.

2.14 Different Levels of Velocity Shrouds

In another embodiment, the vent arrangement may include a cluster ofvent orifices distributed over a portion of the frame for gas washout.In FIGS. 2-10-1 and 2-10-2, the vent orifices 928 are arranged within acircular area having a diameter d, and the orifices 928 have differentsizes.

In the illustrated embodiment, the cluster includes a central or innerorifice 928(1) having a first diameter d1, a plurality of middleorifices 928(2) (e.g., six orifices) regularly spaced and separated fromone another along a circle about the inner orifice 928(1) and eachhaving a second diameter d2 that is larger than diameter d1, and aplurality of outer orifices 928(3) (e.g., eight orifices) regularlyspaced and separated from one another along a circle that is concentricwith the middle orifices 928(2) and each having a third diameter d3 thatis larger than diameter d2.

Similar to the concept described above in section 2.13, the ventarrangement includes adjacent orifices of different size to reducenoise. Specifically, as shown in FIG. 2-10-2, the vent arrangementgradually creates different levels of velocity shrouds going from insideto outside a cluster of vent orifices. As illustrated, the velocityshroud is highest on the inner orifice 928(1) and lowest on the outerorifices 928(3) to help reduce the velocity gradient between the highestvelocity, central stream and the slow moving ambient air. However, itshould be appreciated that the number of orifices, size, length,spacing, and/or general layout may include a range of differentpermutations, e.g., non-circular arrangement of orifices.

2.15 Coated, Stainless Steel Mesh

As noted above with respect to FIG. 2-8, a portion of the mask may beprovided with a stainless steel mesh that includes plurality of ventorifices for gas washout. In an embodiment, the stainless steel mesh maybe heavily coated with a hydrophobic material. If the hydrophobiccoating is sufficiently thick, the coating can help to block up thetypically large orifice size defined in stainless steel woven meshessuch as the mesh 742 described above.

2.16 Hydrophobic Meshes

In an embodiment, a hydrophobic mesh/fabric such as that described abovemay be a medical grade filtration mesh with an extremely consistent,fine, orifice size, e.g., mesh and fabric available from Sefar.

2.17 Slot-Orifice Vent

In another embodiment, as shown in FIG. 2-11, the mask may include avent orifice 1028 and a cap 1050 that covers the vent orifice 1028 todefine a small gap or vent passage 1026 that directs gas washout to anoutlet remote from the mask, e.g., similar to the slot-orifice vent inResMed's UltraMirage mask. The cap 1050 may include an arcuate portion1051 adjacent the vent outlet.

The thin slot or vent passage 1026 provides for much greater effectivearea to encourage a long flow path to fully develop flow, therebyreducing the amount of generated vent noise. The effective venting areais just the area of the small orifice at 1028. However, the relativelylarge vent cap radius, half d1, provides for a long flow path.

2.18 Balance of Cleanability and Quietness of Orifice Size

In another embodiment, the orifice size may be selected so that it isboth cleanable and quiet. In an exemplary embodiment as shown in FIG.2-12, for a mask having a frame thickness of about 1.7 mm, the diameterrange between d1 and d2 of the orifice may be between about 0.4-0.8 mm.As illustrated, a larger diameter orifice is easier to clean, howeverthe larger the orifice the nosier the orifice. Such orifice size mayvary, e.g., depending on frame thickness, desired cleanability and/orquietness, etc.

2.19 Fold-A-Vent

In another embodiment, the mask vent may be in the form of an insertthat is provided to a mask (e.g., snap-fit into position) and defines aplurality of vent orifices. In an embodiment, as shown in FIGS. 2-13-1to 2-13-3, the insert 1160 is constructed of a molded/stamped sheet ofplastic (e.g., polypropylene with thickness in the range of about0.5-0.8 mm) having a plurality (e.g., FIG. 2-5 or 3) of perforatedsections 1162(1), 1162(2), 1162(3) that are folded against each other toproduce a three-dimensional matrix of finer, porous vent orifices.

As illustrated, the first section 1162(1) includes a series of slots1163(1) arranged at a first angle, the second section 1162(2) includes aseries of slots 1163(2) arranged at a second angle, and the thirdsection 1162(3) includes a series of slots 1163(3) arranged at a thirdangle. In the illustrated embodiment, the first angle is about 135° fromhorizontal, the second angle is about 45° from horizontal (i.e.,perpendicular to the first angle), and the third angle is vertical orabout 90° from horizontal. However, the slots may be arranged at othervarying angles. Also, each of the slots has a similar width. However,the slots may have varying widths, which may vary from slots in othersections.

The sections 1162(1), 1162(2), 1162(3) are joined to one another byintegral hinges 1164 (e.g., reduced width, slotted edges betweensections) to facilitate folding. Also, ends of the first and thirdsections 1162(1), 1162(3) may includes locking snaps or tabs 1165structured to retain the insert in its folded configuration.

When in its folded configuration, the slots 1163(1), 1163(2), 1163(3)overlap one another to provide fine, porous vent orifices through theinsert 1160. The insert 1160 may be unfolded or opened for cleaningand/or quick drying.

2.20 Stack-A-Vent

FIGS. 2-14-1 to 2-14-3 illustrate another embodiment of a vent insert1260 for a mask. In this embodiment, the vent insert 1260 includes aplurality of grill components 1270(1), 1270(2), 1270(3), 1270(4) (alsoreferred to as cover members) that are stacked on top of one another toproduce a three-dimensional matrix of finer, porous vent orifices.

As illustrated, the vent insert 1260 includes a cylindrical base 1265that provides a flange or shoulder 1266 adapted to support the basewithin an outlet opening in the mask. A grill 1268 (e.g., one or morecross-bars) defining a series of slots or outlet openings 1263 isprovided to an upper portion of the base 1265.

Also, the upper portion of the base 1265 includes an annular rim 1267adapted to support a plurality of disk-like grill components 1270(1),1270(2), 1270(3), 1270(4). In the illustrated embodiment, four grillcomponents 1270(1), 1270(2), 1270(3), 1270(4) are provided to the base1265. However, more or less grill components may be used, e.g., 1, 2, 3,4, or more grill components.

Each disk-like grill component 1270(1), 1270(2), 1270(3), 1270(4)includes a grill 1272 defining a series of slots and an annular rim 1274adapted to interlock with the base 1265 and/or other grill components.Specifically, the upper edge of the annular rim includes diametricallyopposed protrusions 1276 and the lower/outer edge of the annular rimincludes a series of recesses 1278 (e.g., twelve recesses) regularlyspaced and separated from one another.

In use, a first grill component 1270(1) is coupled to the base 1265 byinterlocking selected recesses 1278 with the diametrically opposedprotrusions 1269 provided on the annular rim 1267 of the base 1265. Thefirst grill component 1270(1) may be selectively rotated and interlockedwith the base 1265 in order to adjust the angle of its grill 1272 withrespect to the grill 1268 of the base 1265.

Then, the second grill component 1270(2) may be selectively coupled tothe first grill component 1270(1) by interlocking selected recesses 1278with the diametrically opposed protrusions 1276 provided on the firstgrill component 1270(1). Similarly, the third grill component 1270(3)may be selectively coupled to the second grill component 1270(2), andthe forth grill component 1270(4) may be selectively coupled to thethird grill component 1270(3). In each coupling, the grill components1270(1), 1270(2), 1270(3), 1270(4) may be selectively rotated andinterlocked in order to adjust the angle of the grills 1272 with respectto one another. That is, the grill components 1270(1), 1270(2), 1270(3),1270(4) may be stacked in different configurations to create differentarrays of vent orifices through the insert.

In use, as shown in FIG. 2-14-3, the grill 1268 of the base 1265 and thegrills 1272 of the grill components 1270(1), 1270(2), 1270(3), 1270(4)overlap one another to provide fine, porous vent orifices through theinsert 1260. Each of the grill components or cover members 1270(1),1270(2), 1270(3), 1270(4) includes a surface 1279 that extends over anoutlet of at least one outlet opening 1263. The insert 1260 may beuncoupled or unstacked for cleaning and/or quick drying.

2.21 Single and Double Layer Media

FIGS. 2-15-1 to 2-15-3 illustrate another embodiment of a vent insert1360 for a mask. In this embodiment, the vent insert 1360 includes media1380 (e.g., (anti-bacterial) filter, membrane, fabric, mesh, or otherporous material) to diffuse flow.

As illustrated, the vent insert 1360 includes a cylindrical base 1365that provides a flange or shoulder 1366 adapted to support the basewithin an outlet opening in the mask (e.g., base secured to mask byfriction-fit, adhesive, etc.). A grill 1368 (e.g., one or morecross-bars) defining a series of slots is provided to a lower portion ofthe base 1365. The grill or cross-bar(s) 1368 prevents inadvertenttouching of the vent media during mask handling, and thereby minimizesthe contamination of the vent media through handling.

The upper portion of the base 1365 includes an annular rim 1367 adaptedto support at least one or more media 1380, e.g., one or more layers,e.g., two layers. Also, a plurality of snap-fit tabs 1375 (e.g., foursnap-fit tabs) extend upwardly from the rim. The tabs 1375 are adaptedto interlock with a cover 1385 structured to maintain the media 1380within the base 1365.

The cover 1385 includes an annular side wall 1386 and a cross-bar 1387.An edge of the side wall includes an engagement flange 1386(1) adaptedto engage within a recess 1375(1) provided in each of the tabs 1375 witha snap-fit. The cross-bar 1387 prevents inadvertent touching of the ventmedia during handling of the mask to minimize contamination of the ventmedia (e.g., from body oils, hand moisturizers, etc.).

In use, at least one media 1380 is selected (e.g., (anti-bacterial)filter, membrane, fabric, mesh, or other porous material) and insertedwithin the base 1365, and the cover 1385 is snap-fit to the base 1365 toretain the media 1380 therein. As shown in FIG. 2-15-3, the vent flow isdiffused as it passes through the grill 1368 and media 1380 of theinsert 1360, which reduces noise. The cover 1385 may be removed to cleanand/or replace the media 1380.

In an embodiment, the base 1365 and cover 1385 may be molded of aplastic material to define a plastic casing for the at least one media1380. The at least one media 1380 may be overmolded or adhered to thecasing. In such arrangement, the entire vent insert 1360 may be replaced(i.e., replaceable cartridge), rather than replace the individual media.

2.22 Double Layer Media with Expansion Chamber

FIGS. 2-16-1 to 2-16-3 illustrate another embodiment of a vent insert1460 for a mask. In this embodiment, the vent insert 1460 includes twolayers of media 1480(1), 1480(2) (e.g., (anti-bacterial) filter,membrane, fabric, mesh, or other porous material) to diffuse flow.

As illustrated, the vent insert 1460 includes a cylindrical base 1465that provides a flange or shoulder 1466 adapted to support the basewithin an outlet opening in the mask. A grill 1468 defining a series ofslots is provided to a lower portion of the base 1465. The grill 1468prevents inadvertent touching of the vent media during mask handling,and thereby minimizes the contamination of the vent media throughhandling.

The upper portion of the base 1465 includes a lower annular rim 1467(1)adapted to support a first media 1480(1) and an upper annular rim1467(2) adapted to support a second media 1480(2). Also, an engagementflange 1475 extends upwardly from the upper rim and is adapted to engagea cover 1485 structured to maintain the first and second media 1480(1),1480(2) within the base 1465.

The cover 1485 includes a ring portion 1486 and a cross-bar 1487. Anedge of the ring portion 1486 is adapted to engage the flange 1475provided to the base 1465. The cross-bar 1487 prevents inadvertenttouching of the vent media during handling of the mask to minimizecontamination of the vent media (e.g., from body oils, handmoisturizers, etc.).

Further, the perimeter of the base 1465 includes a recessed side walland a series of slots 1482 extending through the side wall. Acylindrical band 1483 (e.g., filter or other suitable permeable media)is provided to the recessed side wall and covers the slots 1482.

In use, a first media 1480(1) is selected (e.g., (anti-bacterial)filter, membrane, fabric, mesh, or other porous material) and insertedinto the lower rim 1467(1) of the base 1465, a second media 1480(2) isselected (e.g., (anti-bacterial) filter, membrane, fabric, mesh, orother porous material) and inserted into the upper rim 1467(2) of thebase 1465, and the cover 1485 is engaged with the base 1465 to retainthe media 1480(1), 1480(2) therein. As illustrated, the cover 1485includes an annular protrusion 1469 adapted to engage an upper surfaceof the second media 1480(2) to secure the same in position. It should beappreciated that the first and second media may include similarstructures (e.g., material, thickness, etc.), or the first and secondmedia may include structures that are different from one another. Also,the first and second media may include different diameters (asillustrated) or the first and second media may include similar diameters(with the base structured to support the same).

As shown in FIG. 2-16-3, the vent flow is diffused as it passes throughthe grill 1468 and first and second media 1480(1), 1480(2) of the insert1460, which reduces noise. In addition, the vent flow may pass throughthe slots 1482 and band 1483 between the first and second media 1480(1),1480(2) to diffuse the flow. The cover 1485 may be removed to cleanand/or replace the first and second media 1480(1), 1480(2). Utilizing anarrangement of double layer vent media compared with a single layer ofvent media allows the use of more permeable, open-structured weaves. Thelarger orifices of these more open-weaves are less likely to occludewith debris, humidity and saturation. More open-weaves are also easierto clean.

2.23 Pleated Media

FIGS. 2-17-1 to 2-17-3 illustrate another embodiment of a vent insert1560 for a mask. In this embodiment, the vent insert 1560 includespleated media 1580 (e.g., (anti-bacterial) filter, membrane, fabric,mesh, or other porous material) to diffuse flow.

As illustrated, the vent insert 1560 includes a cylindrical base 1565that provides a flange or shoulder 1566 adapted to support the basewithin an outlet opening in the mask. A grill 1568 defining a series ofslots is provided to a lower portion of the base 1565. The grill 1568prevents inadvertent touching of the vent media during mask handling,and thereby minimizes the contamination of the vent media throughhandling.

The upper portion of the base 1565 includes an annular rim 1567 adaptedto support media 1580 having a plurality of pleats or folds. Also, anengagement flange 1575 extends upwardly from the rim and is adapted toengage a cover 1585 structured to maintain the media 1580 within thebase 1565.

The cover 1585 includes a ring portion 1586 and a cross-bar 1587. Thecross-bar 1587 prevents inadvertent touching of the vent media duringhandling of the mask to minimize contamination of the vent media (e.g.,from body oils, hand moisturizers, etc.). The edge of the ring portion1586 includes a recess and adapted to engage the flange 1575 provided tothe base 1565.

In use, a pleated media 1580 is selected (e.g., (anti-bacterial) filter,membrane, fabric, mesh, or other porous material) and inserted withinthe base 1565, and the cover 1585 is engaged with the base 1565 toretain the media 1580 therein.

As shown in FIG. 2-17-3, the vent flow is diffused as it passes throughthe grill 1568 and the pleated media 1580 of the insert 1560, whichreduces noise. The cover 1585 may be removed to clean and/or replace thepleated media 1580. The use of pleated media allows for a greater areaof lower air permeability, venting media to be used whilst stillmaintaining the footprint within a relatively small area. The lower theair permeability of the venting media, the more effective it is atreducing noise and diffusing air flow as it is much more restrictive toflow.

2.24 Media to Diffuse Flow

In embodiments described above, media (e.g., (anti-bacterial) filter,membrane, fabric, mesh, or other porous material) may be provided to thevent arrangement (e.g., vent insert) to diffuse flow. Media may beselected from a range of materials, properties, and manufacturers.

For example, exemplary media may be disposable and/or hydrophobicallytreated and may be in the form of a plastic mesh, stainless steel mesh,3D spacer fabric, felt, and/or membranes (e.g., PALL, Gore-Tex, GEEnergy). Specific examples include PALL BB Filter (hydrophobic), GEEnergy ePTFE membrane, Gore-Tex ePTFE membrane, Sefar PP mesh05-1001-K120, Sefar PP mesh 05-1001-1(079, Sefar PP mesh 05-8000-K085,3D spacer fabric SPC-121, Sefar SS mesh 165/1400, Sefar PET mesh07-88-1(080 double layer, Sefar PET mesh 07-88-K080 double-layer-gap,Sefar PET mesh 07-88-1(060 double layer, Sefar NFW-PEPE-384-CS17,Transpor Drylayer woven wicking fabric, reticulated foam, and/or 3M8710E non-woven.

Advantages of the plastic mesh include: hydrophobic treatment, smallfootprint, humidification, biocompatible, and/or simple automatedpunching and overmolding. Advantages of the stainless steel mesh includehigh perceived value, robustness, and/or biocompatible. Advantages ofthe 3D spacer fabric include small footprint and/or humidification.Advantages of the felt include semi-hydrophobic, control of permeabilitywith density, and/or less expensive. Advantages of the membranes includepleating, cost, hydrophobic. “high tech”, and/or biocompatible.

In an embodiment, the media may be constructed of an electricallyconductive material that allows a current to pass through the media,e.g., to dry the media during and/or after use and prevent water vaporfrom clogging the vent openings.

2.25 Common Component

As noted above, the vent arrangement may be a common componentstructured for use in multiple interface types. For example, FIGS.2-18-1 to 2-18-3 illustrate the vent insert 1360 shown in FIGS. 2-15-1to 2-15-3 provided to three different types of interfaces. In FIG.2-18-1, the vent insert 1360 is attached to the mask frame 1624 of amask. In FIG. 2-18-2, the vent insert 1360 is attached to the mask elbow1627 of a mask. In FIG. 2-18-3, the vent insert 1360 is attached to theend of a frame 1629 for a nasal prong arrangement. Theinterchangeability of the vent insert 1360 facilitates manufacturing andreplacement.

2.26 Annular Vent

As noted above in FIG. 1-1, vent flow for a single large outlet with arelatively short flow path produces relatively high velocity flow. Suchhigh velocity flow is considered a “jet stream”, generating largechanges in speed directly outside the outlet. Such arrangement generateshigh jet noise.

Since the noise level is determined by the speed of the jet stream inrelation to the speed of the surrounding air, noise production can begreatly reduced by using an extra air stream with a lower speed outsidethe jet stream as shown in FIG. 2-19 (i.e., central higher-velocitystream and outer lower-velocity streams. As illustrated, the graduatedchange in speed across the streams is less than that of a single streamto ambient air. FIG. 2-19 is a schematic of the velocity shroudsdescribed above with respect to FIG. 2-10-2 for example.

FIG. 2-20 illustrates an embodiment of a dual flow mouthpiece 1790 foran air compressor. This embodiment is an example illustrating anapplication of the theory in FIG. 2-19 to reduce noise of the jetstream. As illustrated, the dual flow mouthpiece 1790 includes a centralconduit 1792 that provides a fast inner stream and an outer annularconduit 1794 that provides a slow outer stream. Such arrangementproduces less noise than a mouthpiece having a single conduit or stream.

FIGS. 2-21-1 to 2-21-4 illustrate an elbow assembly 1845 according to anembodiment of the present invention. The elbow assembly 1845 includes avent arrangement that allows part of the vented gas to move at a slowerspeed outside a faster central stream to reduce noise. Such ventarrangement may be adapted for use with elbow assemblies described inU.S. Provisional Application No. 60/924,359, filed May 10, 2007, whichis incorporated herein by reference in its entirety. However, it shouldbe appreciated that such vent arrangement may be applied to otherportions of a mask, e.g., mask frame.

As shown in FIGS. 2-21-1 to 2-21-4, the elbow assembly 1845 includes anelbow 1846 and a cover 1850 releasably attached to the elbow 1846. Theelbow 1846 includes a first end 1846(1) for releasably engaging with anopening in a mask frame and a second end 1846(2) for releasably engagingwith a swivel. Each of the first and second ends 1846(1), 1846(2)include a plurality of resilient flexible arms 1847 adapted to engagethe frame/swivel with a snap-fit.

The main body of the elbow 1846 includes a venting area which includes aplurality of vent orifices 1828 for gas washout. As best shown in FIGS.2-21-3 and 2-21-4, each vent orifice 1828 tapers from a smallercross-section at the vent inlet to a larger cross-section at the ventoutlet. A pair of lugs 1848 (only one being visible in FIG. 2-21-1) areprovided on opposing sides of the venting area. The lugs 1848 areadapted to engage respective retaining members 1851 (see FIG. 2-21-2)provided on an inside surface of the cover 1850. Also, one or more tabs1849 (see FIG. 2-21-1) are provided to the main body of the elbow 1846to space the cover 1850 away from the outer surface of the main body. Inan alternative embodiment, the taper direction of the vent orifices maybe reversed, i.e., from larger cross-section at the inlet to smallercross-section at the outlet.

As shown in FIG. 2-21-2, the elbow 1846 includes a baffle 1852 adjacentto where the elbow 1846 is attached to the mask frame. The baffle 1852has a generally U-shape and is arranged to divide the upper arm of theelbow into an air delivery passage and an exhaust passage.

The cover 1850 includes a venting area which includes a plurality ofvent clusters 1854 for gas washout. Specifically, each vent cluster 1854includes a tubular spigot that defines an orifice 1856 that tapers froma larger cross-section at the inlet to a smaller cross-section at theoutlet, and a plurality of arcuate shaped orifices 1858 (e.g., 4orifices) regularly spaced and separated from one another along a circleabout the spigot and each having a cross-section that tapers from alarger cross-section at the inlet to a smaller cross-section at theoutlet. In an alternative embodiment, the taper direction of theorifices may be reversed, i.e., from smaller cross-section at the inletto larger cross-section at the outlet.

In the connected position, the venting area of the cover 1850 is alignedwith the venting area of the elbow 1846 to define vent flows with afaster inner stream and a slower outer stream as shown in FIG. 2-21-3.Specifically, each vent cluster 1854 of the cover 1850 is aligned with arespective orifice 1828 of the elbow 1846 such that the spigot of eachvent cluster 1854 extends partially within the respective orifice 1828of the elbow 1846.

In use, vent flow passes through the orifices 1828 of the elbow 1846 andinto respective vent clusters 1854 of the cover 1850. As shown in FIG.2-21-3, the flow passing through the orifice 1856 of the spigot isfaster than the flow passing through the orifices 1858 outside thespigot. The extra, slower outer stream can reduce vent noise in use.

Such arrangement also allows pins with a thickness of 0.7 mm or less tobe used to mold very small holes, i.e., the arcuate orifices 1858 aroundthe central orifice 1856. In known embodiments, normal molding pinshaving a diameter of less than 0.7 mm are not particularly robust foruse in tooling for molds.

In an embodiment of the vent arrangement, as shown in FIG. 2-21-4, D₁may be about 1.76 mm, D₂ may be about 0.7 mm, D₃ may be about 0.3 mm, D₄may be about 1.13 mm, D₅ may be about 1.6 mm, D₆ may be about 2.6 mm, D₇may be about 2.5 mm, D₈ may be about 1.5 mm, and D₉ may be about 2 mmAlthough specific dimensions and ranges of the vent arrangement areindicated, it is to be understood that these dimensions and ranges aremerely exemplary and other dimensions and ranges are possible dependingon application. For example, the exemplary dimensions may vary by 10-20%or more or less depending on application.

2.27 Protrusions with Vents

FIGS. 2-22-1 and 2-22-2 illustrate a vent arrangement 2000 according toanother embodiment of the present invention. In this embodiment, thevent arrangement 2000 includes one or more protrusions 2002 provided toa venting area 2004 of the mask, and one or more vent openings 2006 areprovided in side walls of each protrusion 2002 to vent washout gas. Inaddition, one or more vent openings 2008 may be provided in the ventingarea adjacent the protrusions 2002 to vent washout gas. In use, washoutgas from the vent openings 2006 in the protrusions 2002 and washout gasfrom the vent openings 2008 in the adjacent venting area are directedinto one another to diffuse the air flow, which results in more diffusedventing. Alternatively, the adjacent streams may also be slightly offsetto avoid direct collision of the streams to minimize turbulent noise yetstill provide some degree of diffusion.

In the illustrated embodiment, the venting area 2004 provides a basewall 2005 and the plurality of protrusions 2002 extend outwardly fromthe base wall 2005. As illustrated, each protrusion 2002 is in the formof a truncated pyramid, and a vent opening 2006 is provided through eachside wall of the pyramid, i.e., four vent openings 2006 per pyramid.However, it should be appreciated that any suitable number of openingsmay be provided to each pyramid, e.g., multiple openings in each sidewall, opening in only selected side walls, opening in at least one sidewall, etc. Also, in the illustrated embodiment, each opening 2006 has agenerally trapezoidal shape, e.g., height of about 0.2-0.6 mm (e.g., 0.4mm). However, the openings may have other suitable shapes, sizes, and/orarrangement, e.g., circular, tapered along its length, etc.

As shown in FIG. 2-22-1, the protrusions 2002 are arranged corner tocorner in a spaced-apart, grid-like manner Such arrangement definesmultiple venting areas between the protrusions 2002 in which respectivevent openings 2008 are provided. However, other suitable arrangements ofthe protrusions are possible, e.g., random, circular, rows, columns,etc. In addition, it should be appreciated that more than one opening2008 may be provided in each venting area defined between protrusions2002. Also, openings 2008 may simply not be provided.

In the illustrated embodiment, each opening 2008 has a generallycircular shape. However, the openings 2008 may have other suitableshapes, sizes, and/or arrangement, e.g., non-circular, tapered along itslength, etc.

The protrusions 2002 are structured to increase the surface areaavailable for venting so more vent openings may be provided over aventing area of the mask. For example, in the illustrated embodiment,the protrusion 2002 provides four vent openings 2006 in a similar areaas each vent 2008.

In use, the vent openings 2006 in the protrusions 2002 and the ventopenings 2008 in the base wall 2005 are arranged so that washout gas isdirected in different directions, into one another and/or slightlyoffset from one another to create diffuse air flow, e.g., see FIG.2-22-1.

It should be appreciated that the protrusions may have other suitableshapes or arrangements. For example, the protrusions may be star-shaped,crescent-shaped, alpha-numerically shaped, logo-shaped, hexagonal,octagonal, etc. That is, the protrusions may have any suitable shapewith vent openings arranged to deliver exhaust gases in a direction thatis not parallel to adjacent vent orifices. Also, as shown in FIGS.2-22-3 and 2-22-4, the lower edge of the vent openings 2006 may alignwith the base wall 2005, rather than be spaced upwardly from the basewall 2005 as in FIGS. 2-22-1 and 2-22-2. Additionally, the inner basewall or interior surface of protrusion 2002 may be shaped rather thanplanar (as shown in FIGS. 2-22-2 and 2-22-4), for example angular orrounded. This arrangement may direct the air stream out of vent openings2006 in a smoother pathway, thereby reducing turbulent flow and thusnoise.

FIG. 2-22-5 is a schematic view of a mold for molding the protrusions ofFIGS. 2-22-3 and 2-22-4. As illustrated, upper and lower molds UM, LMcooperate to define the top of the protrusions, the base wall, and thevent openings there between.

In another example, as shown in FIG. 2-23, each of the protrusions mayhave an inverted configuration, e.g., truncated pyramid-shaped recessthat extends inwardly from the base wall 2005 and into the breathingcavity. In such arrangement, a vent opening 2007 may be provided in thebottom wall of each truncated pyramid-shaped recess rather than the basewall 2005 to create diffuse flow.

In another example, as shown in FIG. 2-24, each protrusion may have adome-shape with vent openings 2006 provided along the dome.

In yet another example, as shown in FIG. 2-25, each protrusion may be inthe form of an elongated three-dimensional trapezoid with vent openings2006 along side walls thereof. As illustrated, the 3-D trapezoids may bespaced apart to define venting areas there between in which ventopenings 2008 are provided.

In an embodiment, the protrusion may be provided as a separate componentfrom the mask that is adapted to be attached or retrofit to the maskincluding one or more vent openings. That is, the protrusion may besecured in position (e.g., glued, snap-fit, etc.) over a selected ventopening to cover the vent opening and provide diffused vent flow as gaspasses there through in use.

2.28 Disk-Like Vent Arrangement

FIG. 2-26 illustrates a vent arrangement 2100 according to anotherembodiment of the present invention. In this embodiment, the ventarrangement 2100 is structured to be connected between the mask and theair delivery conduit. As illustrated, the vent arrangement 2100 includesa plurality of disks 2195 adapted to be stacked on top of one another. Aplurality of the disks 2195 (e.g., every disk in the stack, every otherdisk in the stack, etc.) include vent openings 2197 (e.g., curvedrecesses) that create passages for diffused vent flow. A longer lengthof the stacked disks may create more diffuse vent flow.

In an embodiment, the disks may be coupled to one another (e.g.,slinky-like arrangement) to create a one-piece structure, e.g., tofacilitate cleaning and reduce the risk of losing small parts.

3.0 Sound Power

FIG. 3 provides a chart illustrating sound power for vent mediadescribed above. As illustrated, at 10 cmH₂O, the sound power for ventmedia described above may range from about 22 dBA to about 45 dBA for aflow rate of about 6-57 L/min, and at 20 cmH₂O, the sound power mayrange from about 28-35 dBA for a flow rate of about 23-42 L/min. Thestandard vent can be, for example, the vent arrangement shown in FIG.4-1A.

The vent media may be selected based on sound requirements, preferences,etc. For example, in an embodiment, the vent may be quieter than about30 dBA. In another embodiment, the vent may be quieter than about 25dBA. The sound power for the vent media may be dependent on thecoarseness of the fibers in each vent media, the size of the holes inthe vent media, and/or the flow path through the vent media.

In an embodiment, the fibers in the vent media may not be coarse so asto avoid turbulent flow. For example, ePTFE membrane may have flaws andvariations throughout the membrane and therefore may cause higher noiselevels particularly at higher flow rates.

In an embodiment, the size of the holes in the vent media may be small,for example, the stainless steel meshes may have small vent holes thatemit an acceptable level of noise.

In an embodiment, the flow path through the vent media may be generallylong and direct, forming for example a continuous tunnel. For example,the flow path through the PP mesh may be more direct (due to thearrangement of fibers) than that through the reticulated foam or wovenwicking fabric thereby reducing the noise emitted from the PP mesh thanthe foam.

4.1 Bayonet Vent

FIG. 4-1A to 4-7D illustrate a vent arrangement according to anotherembodiment of the present invention. In this embodiment, the mask ventis in the form of a vent cap structured to be releasably attached to anopening or venting area of the mask. The vent cover includes a pluralityof vent holes constructed and arranged to diffuse airflow leaving themask in use.

FIGS. 4-1A to 4-1C illustrate vent caps according to alternativeembodiments of the present invention. FIG. 4-1A illustrates a vent cap2200 including multiple vent holes 2230 arranged on a base wall todirect airflow away from the patient's face in use. FIG. 4-1Billustrates a vent cap 2300 including multiple vent holes 2330 arrangedon an annular side wall to provide diffuse airflow that is directed awayfrom the patient's face as well as the bed partner. The angle of thediffused airflow can be tuned by altering the dimensions of the ventcap. FIG. 4-1C illustrates a vent cap 2400 including media 2430 (e.g.,textile, filter, membrane, fabric, mesh, or other porous material ormeans of ventilation) structured to diffuse airflow from the mask.

In each vent cap embodiment, there may be any suitable number of holesdistributed around the vent cap. Each hole may have any suitable shape,e.g., generally round, square, tapered along its length, etc. Also, theholes may be uniform or varying in size and/or shape. In an embodiment,each hole may be no smaller than about 0.00-0.08 mm in diameter.Preferably, each hole may be no smaller than 0.6-0.8 mm (e.g., 0.7 mm)in diameter. Smaller holes may be preferable as they direct air flows insuch a way that they become more fully developed flows. In analternative embodiment, the vent cap may include a venting area adaptedto be aligned with a venting area of the mask (e.g., elbow) whenassembled together to define “full” vent passages, e.g., similar to thearrangement shown in FIGS. 2-21-1 to 2-21-4 described above.

In an embodiment, the vent cap may be made from a polymer, such aspolypropylene or polycarbonate. However, other suitable materials arepossible. Also, the vent cap may be constructed and arranged to berelatively durable, or the vent cap may be constructed and arranged tobe less durable, replaceable, and/or disposable.

The vent cap 2300 will now be described in greater detail. As shown inFIGS. 4-2A to 4-2C and 4-3A to 4-3C, the vent cap 2300 includes a basewall 2335 and a dome 2340 that extends upwardly from the base wall 2335above the horizontal surface of the base wall 2335. As illustrated, themultiple vent holes 2330 are arranged on an annular side wall of thedome 2340.

The dome 2340 may have a generally hemispherical, trapezoidal, square,or other desired shape. Preferably, the dome 2340 has a low profile,e.g., raised 1-3 mm (e.g., 2 mm) from the horizontal surface of the basewall. This arrangement helps to direct air flow in long, thin paths soas to maintain more fully developed and/or laminar flow. Also, the“domed” vent cap directs exhaust flow up and out from the mask, i.e.,“domed” vent cap alternates the direction of exhaust flow from a firstincoming direction d1 to a second outgoing direction d2 that is slopedor angled with respect to the first direction d1, e.g., substantiallyperpendicular, as shown in FIG. 4-3B. In addition, the vent capconstitutes an exhaust divider as the vent holes are arranged to dividethe exhaust flow in different directions as it exits the vent cap. Inthe illustrated embodiment, the vent holes are arranged radially alongthe annular side wall of the dome 2340 to radially divide the exhaustflow in 360°. However, it should be appreciated that the vent holes maybe arranged in other suitable manners along the circumference of thedome, e.g., a portion of the circumference up to 360° (e.g., 270°, 180°,90°, or less and anywhere in between), selected arcs or portions of thecircumference (e.g., selected portions on opposite sides of the dome).Alternative vent hole arrangements on the dome may be selected to directexhaust gas in certain directions, e.g., away from the patient's face orbed partner. Also, as shown in FIG. 4-3B, the vent holes may beconfigured to direct exhaust gas at an angle with respect to horizontal,e.g., vent holes may direct exhaust in direction d2 or at angles α1, α2with respect to d2 (e.g., α1, α2 about 0-) 20°. The dome 2340 may be anysuitable size, but should not be wider than the base wall. The outersurface of the dome 2340 may have a smooth finish, e.g., the vent holes2330 are not raised or sunken into the outer surface of the dome 2340.However, in an alternative embodiment, the holes 2330 may be raised orsunken into the outer surface of the dome 2340.

In the illustrated embodiment, each of the vent caps is structured to bereleasably attached to the mask by means of a bayonet connection.Attachment of the vent cap 2300 to an elbow 2390 of the mask will now bedescribed in greater detail. However, it should be appreciated that thevent cap may be releasably attached to another portion of the mask in asimilar manner, e.g., mask frame. Also, it should be appreciated thatthe vent cap may be attached to the mask in other suitable manners,e.g., snap fit, ultrasonically welded (in which case, it would not be areleasable component), interference fit, sliding fit, permanentlymachined into the mask, etc.

As shown in FIGS. 4-2A to 4-2C and 4-3A to 4-3C, the vent cap 2300includes outer and inner side walls (e.g., see FIG. 4-2B) 2352, 2354that extend downwardly from the base wall 2335 and define a channel 2356there between. Two diametrically opposed projections 2360 extendradially inwardly from the outer side wall 2352. In addition, the ventcap 2300 includes a window 2358 adjacent each projection 2360 thatallows the user to visually recognize when the vent cap 2300 is in alocked position as described below.

As shown in FIGS. 4-5A to 4-5B and 4-7D, the elbow 2390 includes anopening 2392 for gas washout. An annular lip 2394 surrounds the opening2392 and one or more ribs 2396 (e.g., two diametrically opposed ribs)extend radially outwardly from the lip 2394. In the illustratedembodiment, each rib 2396 is generally L-shaped including a first leg2396(1) and a second leg 2396(2). The second leg 2396(2) is a bayonet“stop” which prevents the vent cap from over-turning and subsequentlydisengaging. The second leg 2396(2) also offers feedback to the userthat they have reached the “end” and the vent cap is properly locked.

FIGS. 4-6A to 4-6B and 4-7A to 4-7C illustrate attachment of the ventcap 2300 to the elbow 2390. FIGS. 4-6A to 4-6B illustrate the vent cap2300 in an unlocked position with the vent cap 2300 resting on the elbowlip 2394, i.e., channel 2356 receives elbow lip 2394 and ribs 2396 therebetween. As illustrated, the outer side wall 2352 of the vent cap 2300overhangs the elbow lip 2394 such that the projections 2360 arecircumferentially spaced from the elbow ribs 2396.

The vent cap 2300 is rotatable with respect to the elbow 2390 to movethe vent cap 2300 to a locked position as shown in FIGS. 4-7A to 4-7C.As illustrated, the vent cap 2300 is rotated to position the projections2360 underneath respective first legs 2396(1) of the ribs 2396, andthereby axially lock the vent cap 2300 in position on the elbow 2390.The second legs 2396(2) of the ribs 2396 prevent further rotation of thevent cap 2300 with respect to the elbow 2390, i.e., further rotationcauses projections 2360 to engage respective second legs 2396(2). Asshown in FIG. 4-7B, the window 2358 in the vent cap 2300 allows the userto visually recognize when the first legs 2396(1) of the ribs 2396 arealigned with the projections 2360 and hence locked.

The bayonet connection provides a relatively simple and intuitivearrangement to use. It also minimizes leak from the vent cap since theconnection is radial and does not require an interference to lock thevent cap in position, e.g., like a clip-on vent cover.

In an embodiment, vent cap will diffuse air so that the air flow isundetectable by a person at a distance of less than about 500 mm fromthe vent, e.g., less than 200 mm, less than 100 mm, less than 50 mm,less than 30 mm.

In an embodiment, vent cap will produce less than about 40 dBA soundpower at 10 cmH₂O tested according to ISO3744, e.g., less than 30 dBA,less than 25 dBA, less than 20 dBA.

In FIGS. 4-1A to 4-3B, the vent cap has a generally circular shape.However, the vent cap may have other suitable shapes that allow abayonet connection or other connection mechanism. For example, as shownin FIGS. 4-4A and 4-4B, the vent cap 2300 may include an extended edge2380 that protrudes outwardly from the base wall 2335.

4.2 Super Quiet Diffused Vent

The ideal vent will be quiet and diffuse. Noise can be minimized bypromoting low velocity, fully developed, laminar flow from the vent.Diffuse flow can be achieved by releasing the air flow over a largerarea. Vent arrangements are described below that are structured tominimize noise and diffuse flow from the vent though a combination offeatures.

Additionally, the vent will be able to maintain flow under saturated orhumidified conditions, minimize CO₂ re-breathing, be manufacturable, becleanable or disposable, and biocompatible.

In an embodiment, air flow that is exiting a mask system will bedirected through a vent that is quiet and diffuse. In a preferred form,noise from the vent will be less than about 30-40 dBA, e.g., less than35 dBA. In an embodiment, the vent may be considered “super quiet” whennoise is less than about 30 dBA, e.g., about 20-25 dBA.

It is to be understood that the following embodiments include featuresthat may be incorporated into a mask system individually or incombination.

4.2.1 Baffle

In an embodiment, a baffle 2500 may be provided between a mask 2520 andan elbow 2540 as schematically shown in FIG. 5-1. The baffle 2500 may bepositioned between the elbow 2540 and a frame or cushion of the mask2520 where air is typically vented from the mask 2520. As illustrated,the baffle 2500 is designed to force air exiting the mask 2520 to flowthrough a narrow pathway.

Preferably, as shown in solid lines in the diagram of FIG. 5-2, thebaffle will be wide so that the air will flow through a longer pathway(as compared to a narrow baffle in which the pathway is shorter). Such alonger pathway encourages low velocity, fully developed, laminar flow.

In the illustrated embodiment, the baffle is generally circular.However, the baffle may have any suitable shape that closely matches thegeometry of the elbow to frame or elbow to cushion connection, e.g.,elliptical. In a preferred embodiment, the baffle will be relativelythin to minimize the weight of the mask system. Also, the baffle may notform a completely closed shape, e.g., the baffle may be hemispherical.This arrangement may allow for passage of another apparatus (e.g.,anti-asphyxia valve (AAV)) or easier insertion and removal of thebaffle.

In an embodiment, as shown in FIGS. 5-3-1 and 5-3-2, the baffle 2500 mayhave undulations or curves 2502 to force the air to flow over a largerarea before exiting the mask system. This will slow the flow of the airproducing low velocity, fully developed, laminar flow.

In one form, the baffle may form a part of the elbow. However, thebaffle may be a separate part that may be retrofitted to an elbow. Ifretrofitted, the baffle may be held in place by any suitable means,e.g., interference fit, push fit, adhesive, etc. In the case where thebaffle is to be interference or push fit into the elbow, a lip may beprovided to the baffle to enhance sealing.

In another embodiment, as shown in FIGS. 5-3-1 and 5-3-2 andschematically shown in FIG. 5-4, the baffle may be attached by a bayonetconnection. In the illustrated embodiment, the baffle 2500 includes anannular side wall 2510 with one or more male connectors 2512 provided toan exterior surface of the annular side wall 2510. The elbow 2540includes an annular side wall 2542 with a corresponding number of femaleconnectors 2544 (i.e., L-shaped female connectors) provided to aninterior surface of the annular side wall 2542. In use, the maleconnectors 2512 are received in the first leg 2544(1) of respectivefemale connectors 2544, and then the baffle 2500 and elbow 2540 arerotated relative to one another to slide the male connectors 2512 intothe second leg 2544(2) of respective female connectors 2544.

However, it should be appreciated that other suitable arrangements ofthe bayonet connection may be provided. For example, the baffle mayinclude female connectors for attachment with male connectors on theelbow. Also, the bayonet connection may be positioned on the annularside walls of the baffle and elbow (as shown in FIGS. 5-3-1, 5-3-2, and5-4), or the bayonet connection may be positioned on the mating surfacesof the baffle and elbow (e.g., see FIG. 5-5).

In the illustrated embodiment, the elbow 2540 includes multiple ventholes 2545 arranged on an annular side wall so that the elbow 2540 andbaffle 2550 are arranged to force washout gas generally parallel to theuser's face in use. Typically vents are positioned so that vent flowfrom the mask system is perpendicular to the user's face and maypossibly jet vent flow onto the bed partner or other interferences suchas bedding. Jetting increases noise and discomfort for the bed partner.Vented gas traveling parallel to the user's face tends to avoid theseproblems by “spreading” the vent flow radially over a larger area ratherthan concentrating it all in a small region. That is, the vent flow inthis arrangement is akin to a distributed load rather than aconcentrated load, should it meet with an obstruction in its path.

In one form, the air path 2560 created by the elbow and the baffle willbe about 0.01 to 5 mm, e.g., 1 mm.

In another form, the baffle 2500 may not be anchored in one position.For example, the baffle 2500 may be able to rotate within the elbow2540.

In another form, a series of baffles could be used to force air flow outof multiple air paths. For example, 2, 3, 4, or more baffles may bestacked and placed between the elbow and the mask.

In one form, the baffle may be about 1-30 mm wide (radially), e.g., 10mm wide (radially).

In an embodiment, the baffle may be constructed of a hard plastic, e.g.,such as polycarbonate. Alternatively, the baffle may be constructed fromsofter materials to absorb more of the sound, e.g., low durometersilicone. However, other suitable materials are possible.

In an alternative embodiment, as shown in FIGS. 5-6-1 and 5-6-2, asingle baffle may be used that is coiled to form multiple air paths.FIG. 5-6-1 shows the coil-type baffle 2600 in its uncoiled oruncompressed position, and FIG. 5-6-2 shows the coil-type baffle 2600 inits coiled or compressed position between a mask 2620 and elbow 2640. Asillustrated, the coils cooperate to form multiple air paths along itslength. In an embodiment, one or more grooves may be provided in eachcoil to define air paths across the coil. Such arrangement provides a“stack” of vent rings integrally formed as a one-piece structure.

4.2.2 Tracks or Guides

In an embodiment, tracks or guides may be provided to a vent hole thatare structured to force washout gas to flow in long, narrow passages asit exits the mask system.

For example, FIGS. 5-7-1 and 5-7-2 illustrate an elbow 2740 includingmultiple vent holes 2745 and spaced-apart raised tracks 2747 proximateeach vent hole 2745 along the inner surface of the elbow 2740 (i.e., theside of the elbow that is subjected to the pressurized air flow). In theillustrated embodiment, the tracks 2747 are generally rectangular.However, the tracks may have other suitable shapes to direct washoutgas, e.g., elliptical. In an embodiment, the “track” arrangement mayalso incorporate the use of an annular baffle as shown in FIGS. 5-3-1and 5-3-2.

In an alternative embodiment, the tracks may extend into the innersurface of the elbow 2740. In such embodiment, the tracks would resembleindents or recesses. In use, the indented tracks will draw air flow intothem and create a long, narrow flow path.

In another form, the tracks may be uniform in length. Alternatively, thetracks may vary in length. In an embodiment, the tracks will be longerthan about 2 mm, e.g., 4 mm.

In an embodiment, each vent hole 2745 will have one or more tracksleading to the opening of the hole, e.g., two tracks per vent hole asshown in FIG. 5-7-2. If there is more than one track for each vent hole,the track may be separated by any suitable amount, e.g., more than about0.1 mm.

In an embodiment, the tracks may be molded or otherwise formed into theelbow. Alternatively, the tracks may be provided in a separate component(e.g., molded into separate component) and retrofitted to the elbow.

In another embodiment, two or more tracks may join together or otherwisecooperate about a vent hole to form a tube (or at least a portion of atube). This tube may have a circular cross section, or any other desiredcross section, e.g., square. Similar to the tracks, the tube will directair flow down a long, narrow pathway to form low velocity, fullydeveloped, laminar flow.

4.2.3 Baffle with Tracks or Guides

In an embodiment, a baffle with tracks may be provided to an elbow.

For example, FIG. 5-8-1 illustrates a baffle 2800 including a pluralityof tracks 2802. As illustrated, the baffle 2800 includes a ring-likestructure with each track 2802 extending from an inner radius of thebaffle to an outer radius of the baffle.

In the illustrated embodiment, groups of tracks 2802 are placed aboutthe baffle. However, the tracks may be arranged in other suitablemanners, e.g., continuous around the baffle, randomly arranged.

In the illustrated embodiment, each track 2802 extends into the surfaceof the baffle like an indent or recess. Alternatively, each track may beraised from the surface of the baffle.

In the illustrated embodiment, each track 2802 may be curved from theinner radius of the baffle to the outer radius of the baffle. Thisarrangement maximizes the length of the tracks so that the air travels alonger distance and loses velocity. However, each track may have othersuitable shape along its length, e.g., straight line or coiled extendingfrom the inner radius to the outer radius of the baffle.

As shown in FIGS. 5-8-1 and 5-8-2, the tracks 2802 are provided to oneside of the baffle 2800. However, the tracks 2802 may be provided toboth sides of the baffle (e.g., see FIG. 5-8-3).

FIGS. 5-8-2 and 5-8-3 show the baffle 2800 provided to an elbow 2840. Asillustrated, the elbow 2840 includes one or more windows 2870 about itscircumference adapted to receive the baffle 2800. Specifically, thebaffle 2800 extends through the windows 2870 and includes cutouts 2804to receive elbow wall portions 2872 adjacent the windows 2870. Also, thebaffle 2800 is open ended (e.g., C-shaped) to allow the baffle 2800 todeform slightly during assembly/disassembly to the elbow 2840, e.g.,spring like a circlip.

In an embodiment, the baffle 2800 with tracks on one side may reducenoise from the vent by at least 10 dBA when compared to otherconventional masks (e.g., ResMed's Mirage Micro). In terms of humanhearing, a 10 dBA reduction in noise corresponds to half the amount ofnoise previously emitted. A vent cap (as described above in section 4.1)may reduce noise from the vent by at least 3 dBA when compared to otherconventional masks. A 5 dBA reduction in noise is clearly noticeablewhen compared to the noise previously emitted. A 3 dBA reduction innoise is just noticeable when compared to the noise previously emitted.Therefore, the baffle is highly effective in terms of maximizing noisereduction from the vent and diffusing air flow from the vent.

FIGS. 5-9-1 to 5-9-6 illustrate a baffle or vent ring 3100 for an elbow3140 according to another embodiment of the present invention. Asillustrated, the vent ring 3100 has an open-ended C-shaped main body3101 with L-shaped finger tabs 3103 adjacent the open end (see FIG.5-9-2). The main body 3101 includes a plurality of radially archedtracks or grooves 3102 on one or both sides thereof. The grooves 3102extend from an inner radius of the vent ring to an outer radius of thevent ring.

In the illustrated embodiment, each groove is open-ended (e.g.,U-shaped, V-shaped, semi-circular shaped, etc.) and tapers along itslength from the inner radius to the outer radius of the vent ring. Inaddition, each groove may be radially arched or curved along its length.However, it should be appreciated that each groove may include othersuitable arrangements, e.g., same width along its length, zig-zag orother tortuous path along its length, different size, different depth,extend at different angle along main body (e.g., longest path from innerradius to outer radius of vent ring), etc.

Similar to the baffle 2800 described above, the vent ring 3100 isdeformable (e.g., like a c-clip or circlip) to assemble/disassemble tothe elbow 3140. As best shown in FIG. 5-9-4, the elbow 3140 includes aslot 3142 adapted to receive and support the vent ring 3100 within theelbow 3140. Specifically, the slot 3142 provides an entry/exit window3143 to receive the vent ring 3100, upper and lower flanges 3144, 3145to support the vent ring 3100 within the elbow, and windows 3146 alongwith entry/exit window 3143 that allow gas washout across the vent ring3100, and supporting beams 3148 to maintain and align the vent ring 3100within the elbow 3140.

To assemble the vent ring 3100 to the elbow 3140, the user's fingers maybe placed in the gaps defined by the finger tabs 3103 of the vent ring3100 so as facilitate gripping and squeezing the finger tabs 3103towards one another, which distorts or deforms the generally round ventring into an oval shape (see FIG. 5-9-3). Since the width of thedistorted vent ring 3100 is now less than a width of the entry/exitwindow 3143 of the elbow 3140, the vent ring 3100 may be slid throughthe entry/exit window 3143 and into the elbow 3140 (see FIG. 5-9-4).When the finger tabs 3103 are released, the vent ring 3100 resilientlysprings back into shape. The vent ring 3100 is held in place by aninterference fit, where the width of the vent ring 3100 is substantiallythe same as that of the entry/exit window 3143. In addition, the ventring 3100 includes cutouts 3104 to receive supporting beams 3148 of theelbow 3140 (see FIGS. 5-9-1 and 5-9-5).

Due to forces applied to the vent ring 3100 for insertion and removalfrom the elbow 3140, the vent ring 3100 may be made from a substantiallyrigid or semi-rigid material. Also, the elbow 3140 provides flanges3144, 3145 on opposing sides of the vent ring 3100 to support the ventring 3100 when it is loaded (e.g., pressurized gas flow), therebypreventing bowing of the vent ring 3100 and thus leak (see FIG. 5-9-6).

In use, the grooved vent ring combines with the elbow to define ventorifices, i.e., each vent orifice defined by a part of the vent ring(the groove) and a part of the elbow (upper and/or lower flange). Thus,vented gas escapes along the one or more tracks or grooves between anouter surface of the elbow and the vent ring.

FIGS. 5-10-1 to 5-10-3 illustrate a vent ring 3200 according to anotherembodiment of the present invention. In this embodiment, the vent ring3200 includes a hinge or movable joint 3290 and a locking mechanism 3292diametrically opposed from the hinge 3290. When the locking mechanism3292 is unlocked, the hinge 3290 allows the vent ring 3200 to pivot openand be wrapped around the slot 3142 in the elbow 3140 (see FIG. 5-10-2).In the illustrated embodiment, the locking mechanism 3292 includes a pinand groove arrangement wherein the pin 3292(1) and groove 3292(2) can bepushed together and interlocked (see FIG. 5-10-1) to close the arms ofthe vent ring 3200 around the slot. The groove 3292(2) may be providedto a finger tab 3293 with an arched protrusion 3294 to facilitate grip.Also, as illustrated, the hinge 3290 is provided by a thinned region ofthe vent ring 3200 (e.g., cutout 3204 and slot 3291). The vent ring 3200should be somewhat flexible to allow the vent ring 3200 to be deformed(hoop stress) into an unlocked or open position for assembly to theelbow 3140.

Similar to the above, the vent ring 3200 includes a plurality ofradially arched tracks or grooves 3202 on one or both sides thereof.When grooves 3202 are provided on both sides, it is preferable to havethe grooves 3202 extending in opposite directions on opposing top andbottom sides so that air streams are exhausted in opposite directions(see FIG. 5-10-3), which provides more diffuse exhaust.

FIGS. 5-11-1 and 5-11-2 illustrate a vent ring 3300 and elbow 3340according to another embodiment of the present invention. In thisembodiment, the vent ring 3300 is soft and flexible and includes aclosed, o-ring shape so that the vent ring 3300 can be stretched orwrapped around the elbow 3340. A finger tab 3303 is provided to the ventring 3300 to facilitate assembly/disassembly to the elbow 3340.

The elbow 3340 includes a slot 3342 around its perimeter to receive thevent ring 3300. The bottom wall of the slot 3342 includes openings 3346for gas washout and each side wall of the slot 3342 (adjacent eachopening 3346) includes a plurality of tracks or grooves 3302. Thus, nogrooves are provided on the vent ring 3300, rather the grooves 3302 areprovided on the elbow 3340. In use, the vent ring 3300 forms a seal withthe elbow 3340 so that air can only exhaust between the vent ring 3300and the grooves 3302 on the elbow 3340. Also, the soft and flexible ventring 3300 may dampen sound in use.

FIGS. 5-12-1 and 5-12-2 illustrate a vent ring 3400 and elbow 3440according to another embodiment of the present invention. Thisembodiment is similar to the embodiment of FIGS. 5-11-1 and 5-11-2; incontrast, grooves 3402 are provided on the vent ring 3400, and nogrooves are provided on the elbow 3440 (e.g. smooth surface on sidewalls of the slot 3442). The bottom wall of the slot 3442 includesopenings 3446 for gas washout. This arrangement may be easier tomanufacture.

As illustrated, the vent ring 3400 includes a plurality of tracks orgrooves 3402 along the entire perimeter of the vent ring 3400. Thisarrangement provides 360° vent flow which may provide more diffuseexhaust. In an embodiment, a section of the vent ring 3400 may not havegrooves, and this section could be aligned with the patient's eyes sothat air flow does not irritate the patient's eyes in use.

5. One-Piece Elbow with Integral Diffused Vent Cap

FIGS. 6-1 to 6-7 illustrate an elbow 3040 including a vent arrangementaccording to another embodiment of the present invention. In thisembodiment, the vent arrangement is in the form of a diffused vent cap3000 that is integrally formed in one-piece with the elbow 3040. Thisarrangement provides a single piece elbow with no removable parts, e.g.,so patients do not have to disassemble the elbow for cleaning. Inalternative embodiments, the vent cap may be integrally formed in onepiece with other portions of the mask, e.g., mask frame, associatedconduit, etc.

As illustrated, the elbow 3040 includes a first end 3040(1) forreleasably engaging with an opening in a mask frame and a second end3040(2) for releasably engaging with a swivel. In the illustratedembodiment, the first end 3040(1) includes opposing ribs 3046 adapted toengage the mask frame with a snap-fit. The first end 3040(1) may alsohave a long sealing surface 3041 adapted to interface with the maskframe, whereby such a long sealing surface promotes better sealingthereby reducing leak between the elbow and mask frame. Also, thesealing surface 3041 may be frosted or textured to prevent noise (forexample squeak) created by the friction of two moving parts. The firstend 3040(1) may also have a stepped arrangement whereby sealing surface3041 is wider than stepped surface 3042. This may allow for easierdisassembly of the elbow from the mask frame. Additionally, scallops orcut outs 3043 may be provided to stepped surface 3042 to allow thestepped surface 3042 to flex inwards thereby enabling disassembly of theelbow from the mask frame. The second end 3040(2) includes a pluralityof resilient flexible arms 3047 adapted to engage the swivel with asnap-fit. However, the first and second ends 3040(1), 3040(2) mayinclude other suitable structures for engaging the frame/swivel.

The main body of the elbow 3040 includes a vent cap 3000 integrallyformed in one-piece therewith. Similar to the vent cap 2300 describedabove, the vent cap 3000 includes a base wall 3035, a dome 3045extending upwardly from the base wall 3035, and multiple vent holes 3030arranged on an annular side wall of the dome 3045 to provide diffuseairflow that is directed away from the patient's face as well as the bedpartner. The angle of the diffused airflow can be tuned by altering thedimensions of the vent cap. The diffused airflow provides venting over alarger area to avoid jetting and may also reduce noise.

As shown in FIGS. 6-2 and 6-4, the elbow 3040 includes a baffle 3052adjacent to where the elbow 3040 is attached to the mask frame. Thebaffle 3052 has a generally U-shape and is arranged to divide the upperarm of the elbow into an air delivery passage and an exhaust passage,e.g., to enhance CO₂ washout. In the illustrated embodiment, the baffle3052 is integrally formed with the elbow 3040. However, in analternative embodiment, the baffle may be retrofit to the elbow. Gaps3053 are provided on either side of the baffle 3052 from the innersurfaces of first end 3040(1) to allow stepped surface 3042 to freelyflex inwards when assembled and disassembled to the mask frame.

6. Plug Type Vent

FIGS. 7-1 to 7-3 illustrate a plug-type vent 3500 and frame 3540according to another embodiment of the present invention. In thisembodiment, the plug 3500 is soft and flexible and includes a relativelylong and narrow shape (e.g., I-shaped) for insertion into acorresponding I-shaped slot 3542 in the frame 3540.

As illustrated, the plug 3500 includes a base 3501 and a top lip 3503extending from the base 3501. A plurality of tracks or grooves 3502 areprovided along the exterior surface of the base 3501 and the lowersurface of the lip 3503. The bottom wall of the slot 3542 includes anelongated opening 3546 for gas washout. In use, the grooved plug 3500forms a seal with the slot 3542 so that air can only exhaust between theslot walls and the grooves 3502 on the plug 3500. Also, the soft andflexible plug 3500 facilitates attachment to the frame 3540 and maydampen sound in use.

In the illustrated embodiment, the grooves 3502 extend along the entireperimeter of the plug, e.g., 360° vent flow, which may allow vent flowto be directed into the patient's eyes. In an alternative embodiment,the grooves may exit the plug vertically rather than horizontally so asto direct air flow away from the patient's eyes.

FIGS. 8-1 to 8-3 illustrate a plug-type vent 3600 and frame 3640according to another embodiment of the present invention. In thisembodiment, the plug 3600 and corresponding slot 3642 have a generallyv-shaped configuration.

As illustrated, the plug 3600 includes a pair of arms 3608 and aconnecting portion 3609 connecting the arms 3608. A plurality of tracksor grooves 3602 are provided to each arm 3608 and extend along thebottom surface and the outer side of each arm. Each arm of the slot 3642includes an elongated opening 3646 for gas washout.

In use, the grooves 3602 direct vent flow along sides of the frame andavoid exhaust into the patient's eyes. In an alternative embodiment, thegrooves may extend along the inner side of each arm 3608 so that exhaustcould flow out the inner sides and cause air paths to collide.

FIGS. 9-1 to 9-4 illustrate a plug-type vent 3700 and frame 3740according to another embodiment of the present invention. In thisembodiment, the plug 3700 and corresponding slot 3742 have a generallyu-shaped configuration.

As best shown in FIGS. 9-2 and 9-3, the plug 3700 includes a pair ofarms 3708 and a bight portion 3709 connecting the arms 3708. Each arm3708 includes a plurality of tracks or grooves 3702 on one or both sidesthereof and a connecting portion 3711 for engaging the frame 3740. Inaddition, each arm 3708 includes a port cap 3715 extending from theconnecting portion 3711 and adapted to engage a respective port 3745provided in the frame 3740.

The frame 3740 includes a slot 3742 to receive the plug 3700. The bottomwall of the slot 3742 includes one or more openings 3746 for gas washout(see FIG. 9-4). In use, the grooved plug 3700 forms a seal with the slot3742 so that air can exhaust between the slot walls and the grooves 3702on the plug 3700.

As shown in FIG. 9-4, the slot walls define an angle α (e.g., in therange of 5-45°, e.g., 10°) which directs the air stream outwards fromthe slot 3742. Preferably, the angle α is not relatively large so as todirect the air stream onto the patient's chest.

A support beam 3744 is provided in the center of the slot 3742 tomaintain spacing between upper and lower slot walls. A groove 3717 isprovided in the bight portion 3709 of the plug 3700 to receive at leasta portion of the support beam 3744, e.g., to align the plug in the slotand enhance the interference fit. However, it should be appreciated thatmultiple support beams may be provided. In such embodiment, the supportbeams should be sufficiently spaced apart from one another so thatsufficient exhaust gas can enter the grooves 3702 on the plug 3700 toprovide adequate CO₂ washout. In an embodiment, baffles may be providedinside the frame to help with CO₂ washout.

In the illustrated embodiment, the connecting portion 3711 of each armincludes locking bumps 3713(1), 3713(2) on opposing sides thereof, oneof which is adapted to interlock with a retention slot 3747 (see FIGS.9-1 and 9-2) provided to the frame 3740 along the slot 3742 (i.e.,interference fit). A clearance 3749 is provided to the slot 3742opposite the retention slot 3747 to receive the other of the lockingbumps. This arrangement allows the plug 3700 to be assembled in eitherorientation since the plug is symmetrical. However, alignment markingsmay be incorporated into the plug and/or frame to facilitate assembly(e.g., alignment dots, arrows).

As illustrated, the plug 3700 is adapted to wrap around and under aninlet opening 3751 provided to the frame 3740. However, the plug may bepositioned at other suitable locations on the frame.

In the illustrated embodiment, port caps 3715 are integrated orincorporated into the plug 3700 (e.g., integrally formed in one piece).Such one-piece arrangement reduces the number of mask parts, preventsloss and/or misplacement of parts (e.g., port cap retained to plug whenport cap is unplugged from port), and facilitates manufacturing. Itshould be appreciated that any suitable number of port caps may beprovided to the plug. The connecting arm or hinge 3716 connecting eachport cap 3715 to the plug 3700 may have any suitable length or thickness(e.g., arm could be wider, thicker, and/or longer), which may depend onmaterial properties and/or desired assembly/disassembly force. Theconnecting arm 3716 is flexible to allow bending of the connecting armin the plane of the plug 3700 and/or bending or twisting transverse tothe plane of the plug 3700. Also, when removing the port cap 3715 fromthe respective port 3745, the plug 3700 may be maintained in positionwithin the slot 3742, unless removal of the whole plug is desired.

In an embodiment, the plug 3700 is constructed from a soft and flexiblematerial (e.g., silicone, TPE, rubber) to facilitate attachment to theframe and dampen noise in use. In an embodiment, the plug material mayhave little to no moisture retention and may not be prone to creep.Also, the plug may be made from an opaque elastomer and/or may be arelatively large part so that the plug is harder for the patient tolose.

In the embodiment, the plug 3700 may be made by two shot molding, i.e.,a first shot may be made from a more rigid material to form a skeletonand then a second shot may be made from a softer material. Advantages ofsuch construction include structural integrity of the plug, easier andmore accurate assembly/disassembly, and/or soft outside surface todampen noise. In such embodiment, a polypropylene material may be used.

In an alternative embodiment, the groove 3717 in the bight portion 3709and the support beam 3744 of the frame 3740 may not be provided, e.g.,frame may warp out of shape without the support beam. Also, the groove3717 is shown as a thin slot, however it may also be a scalloped, widerslot to avoid concentrated stress at the groove.

In addition, the tracks or grooves 3702 along the plug 3700 arerelatively thin, however it is possible to extend the length of thebight portion and thus the grooves 3702 may be made wider to allow forsufficient gas flow from the vent. Increasing the size of the bightportion will mean that less or no gas flow is directed towards the chestof the patient in use.

In each embodiment described above, it should be appreciated that thevent component may be provided to any portion of the mask, e.g., aportion of the elbow or a portion of the frame. Also, in eachembodiment, the separate vent component may not be completely removablefrom the mask, e.g., the vent component may be partially removed forcleaning while some part of the vent component is permanently attachedto the frame/elbow. This arrangement may reduce the possibility ofincorrect assembly and loss of parts.

Also, in an embodiment, the vent component may be retrofit to anexisting vent opening in a portion of the mask (e.g., elbow or frame).For example, the vent component (e.g., plug-type vent of FIGS. 7-1 to7-3 and 8-1 to 8-3) may be suitably sized to be inserted in the ventopening of an existing mask. In another example, the vent component mayinclude a groove around its periphery, the groove adapted to locate thevent component against a correspondingly sized rim of the vent openingin the mask.

In another embodiment, a mask may be provided with a series ofreplaceable vent components (e.g., series of vent rings or vent plugs)with different venting characteristics (e.g., number of grooves,positioning of grooves, shape of grooves, size of grooves, etc.). Thisarrangement allows a vent component to be selected from the series toprovide a more customized mask system for the patient, e.g., based ontreatment requirement, optimal gas washout, venting direction, soundrequirement, etc.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention. Also, the various embodiments described abovemay be implemented in conjunction with other embodiments, e.g., aspectsof one embodiment may be combined with aspects of another embodiment torealize yet other embodiments. Further, each independent feature orcomponent of any given assembly may constitute an additional embodiment.Furthermore, each individual component of any given assembly, one ormore portions of an individual component of any given assembly, andvarious combinations of components from one or more embodiments mayinclude one or more ornamental design features. In addition, while theinvention has particular application to patients who suffer from OSA, itis to be appreciated that patients who suffer from other illnesses(e.g., congestive heart failure, diabetes, morbid obesity, stroke,bariatric surgery, etc.) can derive benefit from the above teachings.Moreover, the above teachings have applicability with patients andnon-patients alike in non-medical applications.

What is claimed is:
 1. A mask system configured to deliver airpressurized by a flow generator system by at least 4 cm H₂O aboveatmospheric pressure to the airways of a patient to treat sleepdisordered breathing (SDB) by continuous positive airway pressure (CPAP)therapy, the mask system comprising: an elbow; and a vent componentprovided to the elbow, the vent component configured to discharge gasfrom a pressurized interior of the elbow to atmosphere during said CPAPtherapy, the vent component including an annular side wall and aplurality of vent holes for gas washout arranged on the annular sidewall, the plurality of vent holes configured to remain open in use atleast during the inhalation and exhalation phases of the patient'sbreathing cycle for the discharge of gas during CPAP therapy, whereinthe annular side wall comprises a plurality of spaced support walls, andadjacent ones of the plurality of spaced support walls form a respectiveone of the plurality of vent holes, wherein the vent holes are arrangedradially on the annular side wall to radially divide exhaust flow overone or more portions totaling at least 90° of a circumference of theannular side wall so as to diffuse the exhaust flow and reduce noise,and wherein the elbow includes a baffle configured to divide the elbowinto an air delivery passage and an exhaust passage, the exhaust passagearranged to guide washout gas along a flow path to the plurality of ventholes.
 2. The mask system according to claim 1, wherein the vent holesare arranged to radially divide exhaust flow up to 180° of thecircumference of the annular side wall.
 3. The mask system according toclaim 1, wherein the vent holes are arranged to radially divide exhaustflow up to 270° of the circumference of the annular side wall.
 4. Themask system according to claim 1, wherein the vent holes are arranged toradially divide exhaust flow up to 360° of the circumference of theannular side wall.
 5. The mask system according to claim 1, wherein thevent holes are arranged to radially divide exhaust flow in differentdirections.
 6. The mask system according to claim 1, wherein the ventholes are provided along one or more selected arcs or portions of theannular side wall so as to divide exhaust flow along one or moreselected arcs or portions of the circumference of the annular side wall.7. The mask system according to claim 1, wherein the vent holes arearranged to radially divide exhaust flow to avoid direct collisionbetween air exiting adjacent vent holes.
 8. The mask system according toclaim 1, wherein the vent holes are arranged in only a single row orplane over said one or more portions totaling at least 90° of thecircumference of the annular side wall.
 9. The mask system according toclaim 1, wherein the vent component comprises a base wall and a cap wallthat extend parallel to one another, and the annular side wall isarranged between the base wall and the cap wall and extends transverseto the base wall and the cap wall.
 10. The mask system according toclaim 1, wherein the vent holes are constructed and arranged to allowgas washout while allowing a therapy pressure to be maintained.
 11. Themask system according to claim 1, wherein the vent component comprisesat least 20 of said vent holes.
 12. The mask system according to claim1, wherein each of the plurality of vent holes provides an open flowpath from the pressurized interior to atmosphere during CPAP therapy.13. The mask system according to claim 1, wherein the plurality of ventholes are configured to continuously discharge exhaled gas during CPAPtherapy.
 14. A mask system configured to deliver air pressurized by aflow generator system by at least 4 cm H₂O above atmospheric pressure tothe airways of a patient to treat sleep disordered breathing (SDB) bycontinuous positive airway pressure (CPAP) therapy, the mask systemcomprising: a mask component; and a vent component provided to the maskcomponent, the vent component configured to discharge gas from apressurized interior of the mask component to atmosphere during saidCPAP therapy, the vent component including an annular side wall and aplurality of vent holes for gas washout arranged on the annular sidewall, the plurality of vent holes configured to remain open in use atleast during the inhalation and exhalation phases of the patient'sbreathing cycle for the discharge of gas during CPAP therapy, whereinthe annular side wall comprises a plurality of spaced support walls, andadjacent ones of the plurality of spaced support walls form a respectiveone of the plurality of vent holes, wherein the vent holes are arrangedradially on the annular side wall to radially divide exhaust flow overone or more portions totaling at least 90° of a circumference of theannular side wall so as to diffuse the exhaust flow and reduce noise,and wherein the vent component comprises an integral one piececonstruction with the mask component.
 15. The mask system according toclaim 14, wherein the mask component is an elbow.
 16. A mask systemconfigured to deliver air pressurized by a flow generator system by atleast 4 cm H₂O above atmospheric pressure to the airways of a patient totreat sleep disordered breathing (SDB) by continuous positive airwaypressure (CPAP) therapy, the mask system comprising: a mask component;and a vent component provided to the mask component, the vent componentconfigured to discharge gas from a pressurized interior of the maskcomponent to atmosphere during said CPAP therapy, the vent componentincluding an annular side wall and a plurality of vent holes for gaswashout arranged on the annular side wall, the plurality of vent holesconfigured to remain open in use at least during the inhalation andexhalation phases of the patient's breathing cycle for the discharge ofgas during CPAP therapy, wherein the annular side wall comprises aplurality of spaced support walls, and adjacent ones of the plurality ofspaced support walls form a respective one of the plurality of ventholes, wherein the vent holes are arranged radially on the annular sidewall to radially divide exhaust flow over one or more portions totalingat least 90° of a circumference of the annular side wall so as todiffuse the exhaust flow and reduce noise, and wherein the ventcomponent comprises a cap portion arranged to alter the exhaust flowfrom a first incoming direction to a second outgoing direction that issloped or angled to the first incoming direction.
 17. The mask systemaccording to claim 16, wherein the mask component is an elbow.
 18. Themask system according to claim 16, wherein the second outgoing directionis perpendicular to the first incoming direction.